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BULLETIN OF

THE BRITISH MUSEUM

(NATURAL HISTORY)

GEOLOGY VOL. VII 1962-1963

X R U S T E E S OF

THE BRITISH MUSEUM (NATURAL HISTORY)

LONDON : 1964

DATES OF PUBLICATION OF THE PARTS

No. i. isth May ...... 1962

No. 2. 1 5th May .... . 1962

No. 3. 1 4th August ...... 1962

No. 4. i4th August ...... 1962

No. 5. 1 4th August ...... 1962

No. 6. jth December ..... 1962

No. 7. 7th December ..... 1962

No. 8. 8th February ..... 1963

No. 9. gth July ...... 1963

PRINTED IN GREAT BRITAIN BY THOMAS DE LA RUE & COMPANY LIMITED LONDON

2 0

CONTENTS

GEOLOGY VOLUME VII

PAGE

No. i. A new Eocene Primate Genus, Cantius, and a Revision of some allied

European Lemuroids. E. L. SIMONS i

No. 2. The Brachiopod Genus Cyclothyris, E. F. OWEN 37

No. 3. The Trilobites of the Caradoc Series in the Cross Fell Inlier of Northern

England. W. T. DEAN 65

No. 4. Fossil Flora of the Drybrook Sandstone in the Forest of Dean,

Gloucestershire. K. M. LELE & J. WALTON 135

No. 5. Fossil Insects from the Lower Lias of Charmouth, Dorset.

F. E. ZEUNER 153

No. 6. The English Cretaceous Turritellidae and Mathildidae (Gastropoda).

H. L. ABBASS 173

No. 7. The Morphology of Tubicaulis africanus sp. nov. a fossil fern from

Tanganyika. H. S. HOLDEN & W. N. CROFT 197

No. 8. The Ordovician Trilobite Faunas of South Shropshire, III. W. T. DEAN 213

No. 9. The Gastropod Genus Thatcheria and its Relationships. A. J. CHARIG 255

Index to Volume VII 299

7V, /t, V.

A NEW EOCENE PRIMATE

GENUS, CANTIUS, AND A

REVISION OF SOME ALLIED

EUROPEAN LEMUROIDS

E. L. SIMONS

BULLETIN OF

THE BRITISH MUSEUM (NATURAL HISTORY) GEOLOGY Vo1- 7 No. i

LONDON : 1962

A NEW EOCENE PRIMATE GENUS, CANTIUS,

AND A REVISION OF SOME ALLIED

EUROPEAN LEMUROIDS

BY

ELWYN L. SIMONS

Peabody Museum and Department of Geology, Yale University, New Haven, Conn.

Pp. 1-36 ; Pis. 1-3 ; 4 Text-figures

BULLETIN OF THE BRITISH MUSEUM (NATURAL HISTORY)

GEOLOGY Vol. 7 No. i

LONDON: 1962

THE BULLETIN OF THE BRITISH MUSEUM

(NATURAL HISTORY), instituted in 1949, is issued in five series corresponding to the Departments of the Museum, and an Historical series.

Parts will appear at irregular intervals as they become ready. Volumes will contain about three or four hundred pages, and will not necessarily be completed within one calendar year.

This paper is Vol. 7, No. i of the Geological (Palaeontological) series.

Trustees of the British Museum 1962

PRINTED BY ORDER OF THE TRUSTEES OF THE BRITISH MUSEUM

Issued May, 1962 Price Fifteen Shillings

A NEW EOCENE PRIMATE GENUS, CANTIUS, AND A REVISION OF SOME ALLIED EUROPEAN

LEMUROIDS

By ELWYN L. SIMONS

CONTENTS

Page

I. A NEW EUROPEAN OMOMYID Cantius ...... 3

Taxonomic Revision ........ 5

II. REVISION OF THE SPECIES OF Protoadapis Lemoine ... 8

III. NOTES ON Pronycticebus gaudryi GRANDIDIER .... 14

IV. THE TAXONOMIC POSITION OF Anchomomys STEHLIN . . .21 V. RELATIONSHIPS OF EARLY TERTIARY LEMUR-LIKE PRIMATES . 23

VI. CLASSIFICATION OF EUROPEAN EOCENE PRIMATES ... 27

VII. CONCLUSIONS .......... 34

VIII. ACKNOWLEDGEMENTS ......... 34

IX. REFERENCES .......... 34

SYNOPSIS

Cantius, a new European early Eocene lemur-like Primate genus, is described and additions to knowledge of anatomy and affinities for three Eocene lemuroid genera, Protoadapis, Pronyc- ticebus and Anchomomys are made. The significance of the terms " tarsioid " and " lemuroid " is discussed as these concepts bear on a consideration of the relationships of early Cenozoic European and American lemur-like Primates to each other and to contemporary tarsier-like prosimians. The classification of European Eocene Primates is revised from Simpson (1945) and the conclusions drawn that some European Eocene lemuroids may relate closely to subse- quent stocks as well as to American prosimian families contemporary with them.

ABBREVIATIONS

A.M.N.H. — American Museum of Natural History, New York.

B.M.N.H.— British Museum (Natural History).

G.P.I.H. — Geological and Paleontological Institute, University of Halle /Wittenburg.

M.C.Z. — Museum of Comparative Zoology, Harvard.

P.U. — Princeton University.

S.M.G.C. — Sedgwick Museum of Geology, Cambridge.

I. A NEW EUROPEAN OMOMYID CANTIUS

A RECENT examination of fossil mammals from the London Clay at the British Museum (Natural History) resulted in the discovery of an undescribed upper and two partial lower dentitions of Protoadapis eppsi Cooper (1932). The specimens belong to a new genus which can be assigned to the prosimian family Omomyidae.

Gazin (1958 : 47) proposed family status for the Omomyinae, which have previously been ranked as a subfamily of Anaptomorphidae. The latter taxon is now understood to be a separate stock primarily characterized by reduced dental formula and much

GEOL. 7, i. i§

4 A NEW EOCENE PRIMATE GENUS, CANTIUS

enlarged third and fourth premolars. There are at least two European primate species, Cantius eppsi (described below) and Teilhardina belgica, which can best be assigned to the Omomyidae, although each presents some features of difference from typical omomyids. One might establish a new family or subfamily for these European species, but until they are better known such a procedure has little to recommend it.1 Higher categories among early Cenozoic Primates have already been too much multiplied. This may be due principally to the difficulties of grouping species which are usually known only from dentitions, on rare occasions associated with fragmen- tary skeletal materials, and to the emotional element involved in the study of human relatives and ancestors, deservedly criticized by Simpson (1945 : 181) and elsewhere, and which, apparently, has even pervaded some discussions of fossil prosimians. Both Cantius and Teilhardina come from deposits containing Sparnacian (early Eocene) faunas and consequently represent some of the oldest Old World Primates. They are the earliest, in fact, that could possibly be near the basal stock or ancestry of any of the surviving European, Asian, or African members of the order.

Evidence as to whether or not Eocene omomyids were more lemur-like or more tarsier-like is scanty, for skull parts, other than maxillae, are practically unknown in this group. Hiirzeler (1948) appears to be correct in stressing dental similarities between the early Eocene primate Teilhardina, from Belgium, and the much better known necrolemurines. This view is shared by the writer and is also implied by Gazin (1958 : 92). The Necrolemurinae are quite definitely tarsier-like, and close correspondence between premolar and molar cusp patterns in unspecialized necro- lemurines and omomyids reinforces the idea that Omomys and its allies are nearer to true tarsioids than to such distinctly lemuriform Primates as Adapis or Pronycticebus. There is a reasonable probability that necrolemurines, North American omomyids, and even Old World Anthropoidea were derived from a form like the generalized prototarsioid Teilhardina, which has a lower dental formula of 2.1.4.3., and which lacks specializations in known parts that could rule out this possibility. Of course, Teilhardina itself, of Sparnacian Eocene provincial age, occurs too late in time to have such a position.

A skull fragment of an omomyid, Hemiacodon, discussed and illustrated by Gazin (1958 : 55, pi. 4, fig. 4) indicates some expansion of the dorso-frontal area in at least one member of this family — together with reasonably large orbits. Between the orbital apertures the rostrum, however, is relatively broader than in the probably omomyid derived genus Necrolemur, being about as in Microchoerus (S.M.G.C. 9669). In degree of forward rotation the orbits of Hemiacodon appear to be intermediate between these latter two necrolemurines.

Simpson (1940 : 190-197) discussed a pelvis, some vertebrae, and some elements of the hind limb which probably belong to Hemiacodon (A.M.N.H. 12613) and con- cluded that the " skeleton of Hemiacodon, as far as known, is at least as lemuroid as tarsioid, probably more ". Such judgements ultimately depend on how these two

1 It also seems possible that Periconodon, Lushius and Hoanghonius represent three other Old World omomyids. Together with broad similarities in known parts, both of these Primates possess an un- usual cusp on the antero-internal base of the protocone which has been called a pericone. This struc- ture often occurs in Omomys but is known in very few other members of the order. For discussion of Luchius, see Chow (1961).

A NEW EOCENE PRIMATE GENUS, CANTIUS 5

concepts are defined. It seems unlikely that the features of the postcranial skeleton in any Eocene primate would be closely similar to those in a highly specialized modern form like Tarsius. The earliest tarsioid postcranial distinctions remain elusive. Segregating out osteological characters of value in determining earlier radiations of higher categories, or in indicating phyletic relationships, is always difficult and uncer- tain. Nevertheless, an attempt to do so can be made for Tarsius. In the class of late and unusual specializations (of uncertain value in determining tarsioid phylogeny) may be the following characters : (i) Much enlarged orbits with flaring bony rims. (Occurring also, in a somewhat less exaggerated form, among other primarily nocturnal animals, such as Nycticebus, Aotes, owls, etc.) (2) Greatly elongated cal- caneum and astragalus. (This specialization is seen elsewhere in galagos and in an analogous way in anurans.) (3) Fused tibia and fibula. (Such fusion occurs in a variety of hopping tetrapods including many rodents, lagomorphs, in some marsupials and insectivorans, as well as among Aves. See Barnett & Napier (1953 : 12) for further discussion of the adaptive significance of this feature.) Should these charac- ters be relatively recent acquisitions among tarsiines, even the direct Eocene ancestor of Tarsius, in lacking them, would be difficult to distinguish from lemuroids post- cranially. In view of this possibility, evidence provided by the postcranial bones of Hemiacodon appears to be equivocal in relating the animal either to Tarsiiformes or Lemuriformes. What would help to indicate the affinities of such omomyids would be knowledge of such features as the size and shape of component parts of the brain (their size relative to each other), extent of facial shortening, proportions of palate and skull vault, amount of forward shifting of the foramen magnum, and various other characters of the basicranium, particularly degree of inflation of the auditory bullae and mastoid region, and situation or relationships of entocarotid circulation, of the ectotympanic pterygoid alae, and of cranial foramina. Although for omomyids these cranial features are not known they can be observed in Necrolemur, which in most of these areas closely resembles Tarsius, and which dentally (at least) shows affinity with Omomyidae.

As knowledge of the earliest Primates grows with new finds, taxonomic separation, at all grades of classification, can be expected to become more arbitrary. In this respect, some European Primates, particularly Cantius, evidence a closer relationship between Notharctidae and Omomyidae than has previously been documented ; although this possibility was briefly considered by Gazin (1958 : 47). Perhaps both of these families, assuming the two groups deserve separate family status, are not far removed from a common late Paleocene ancestry.

TAXONOMIC REVISION Genus CANTIUS1 nov.

(PI. i)

TYPE SPECIES. Protoadapis eppsi Cooper, 1932. GENERIC CHARACTERS. As for the species.

1 From the Latin for County Kent, England (Cantium, Cantia) in which all specimens of this primate have been discovered and in analogy with such related forms as Washakius, from the North American Eocene.

6 A NEW EOCENE PRIMATE GENUS, CANTIUS

DISCUSSION. Size : Cantius is a large omomyid, intermediate in size between Hemiacodon and Ourayia, but distinctly smaller than any of the species of Protoadapis, and may have been about the size of the living African Giant Galago, Galago crassi- caudatus.

The discovery of a right maxilla with P3-M3 of this species (PL la) from the early Eocene deposits at Abbey Wood, Kent (since Cooper's original description) confirms that the species belongs to a genus distinct from Protoadapis, a conclusion which can also be demonstrated by features of the lower dentition of Cantius eppsi (B.M.N.H., M-I3773) originally reported on by Cooper (1932), and by two other partial lower dentitions found subsequently (PI. ib). Indeed, Cooper himself suggested the possi- bility that the British species belonged to a distinct genus. Re-examination of all available specimens of Protoadapis indicates that this is so.

Some differences between Cantius and Protoadapis (in the lower dentition) are that the former is somewhat smaller, has paraconids on P4, Mx, M2, a much longer and more complex M3 talonid, and a considerably smaller and lower P3. A charac- teristic feature of Protoadapis, sometimes seen in species of the North American genus Pelycodus as well, is that the P3 stands noticibly higher than P4. In Proto- adapis the paraconid decreases in expression posteriorly in the molar series but not in the same way as in Cantius where the paraconid and metaconid are increasingly drawn together in the series M-^g, compare Pis. ib and 3/. Throughout the lower molar series of Protoadapis the paraconid remains widely separated from the meta- conid and in M3 is represented only by a slight crest — still considerably removed from the metaconid. In Cantius paraconids are clearly delimited in all three molars and are nearly as high as metaconids.1

In this progressive alteration of trigonid elements posteriorly Protoadapis resembles closely Notharctus, while Cantius is much more like some specimens of Omomys in which, although a distinct paraconid is retained throughout the lower molars, the paraconid is closer to the metaconid in M^_3 than in Mg. Cantius, in its enlarged and complex M3 talonid, also agrees well with the elaboration of this element in omomyids. Yet another distinction in the lower dentition between Cantius and Protoadapis is that in Cantius a clearly defined paraconid cusp is present in the P4, a structure which never occurs in Protoadapis (see PL 3/, and Stehlin, 1912 : 1282).

Recognition of the Abbey Wood species as generically distinct from Protoadapis was delayed, in part, because of the scarcity of comparative material in European museums. The total number of good specimens belonging to all species of both of these genera is probably less than ten. Nevertheless, the significance of the facts that Cantius, an omomyid, and Protoadapis, a notharctid-like adapid, occur in the European Eocene should be stressed. Knowledge of such ranges gives added import to the more extensively known North American Primates of the omomyid-notharctid type because it indicates that forms closely affined to them were present in the early Tertiary of the Old World. The possiblity is thus strengthened that some North

1 Paraconid and metaconid of the M3 in the holotype of C. eppsi cannot be distinguished, either because of wear or because they are coalesced. In B.M.N.H., M-i^i^ja, b, however, these M3 cusps are separate but closely approximated.

A NEW EOCENE PRIMATE GENUS, CANTIUS 7

American species may approximate morphological, or even linear stages in the ances- try of Old World Primates.

The upper dentition from the Abbey Wood locality (PI. la ; B.M.N.H., M-I5I45)— quite apart from its occluding well with the type lower dentition of Cantius eppsi (both are of the right side) — shows definite omomyid affinities to about the same degree as do the lower teeth. Hence there is little reason to doubt that it can be assigned to Cantius eppsi. Taken as a whole, this upper dentition is close to that of Omomys and of Teilhardina but is one-half larger than that of either of these small Primates. P3 and P4 are rather simple teeth with a constriction between the inner and outer cusps and are similar in conformation to those of Omomys, Teilhardina and Hemiacodon. P3 has but a single outer and inner cusp and is smaller relative to P4 than in some specimens of Omomys. Both P3 and P4 are less crenulate than in Hemiacodon, but exhibit slight enamel wrinkling, particularly on the median slope of P4 protocone. P4 carries a small cuspule on the anterior slope of the outer cusp which occurs also in Hemiacodon and Washakius, but apparently not in typical Omomys. The anterior, median and posterior protocone crests of the P4 of Cantius are situated about as in Washakius (see Gazin 1958, pi. 9, No. i).

An interesting similarity of Cantius to necrolemurines (and to Tetonius as well) is that the posterior protocone crest of M1 and M2 turns down toward the posterolingual part of the basal protocone cingulum, thus breaking the ridge running toward the metaconule. This forms a so-called " nannopithex-fold ". There is, however, practic- ally no indication of an incipient hypocone element, other than a slight thickening of the posterolingual part of the basal protocone cingulum. As in other omomyids the para- and metaconules are distinct on all three upper molars. These elements are usually less well denned in notharctids. Also unlike notharctids Cantius lacks any suggestion of an upper molar mesostyle. Molar para- and metacones are connected by straight crests on their facing slopes, much as in Omomys and Washakius. Nearly continuous lingual and labial basal molar cingula in Cantius are also quite like those of Omomys. Another resemblance to Omomys, to Teilhardina, to some of the more generalized late Paleocene Primates particularly Navajovius, and also to Tetonius is the small size of the M3 compared to M1"2. Para- and metastyle elements are present, as in most omomyids, except on M3 metacone.

The recent identification of an upper dentition of Protoadapis in the collections of the Geological Institute of the University of Halle /Wittenburg makes possible further comparative remarks about it and Cantius. Protoadapis, unlike Cantius, shows no indication in the upper molars of a nannopithex-fold, and the internal cingulum is typically pronounced and continuous around the lingual base of the protocone, the hypocone is large, and there is no indication of a metaconule on any of the upper molars, see PL 3. In these differences from Cantius, Protoadapis more closely resembles the notharctid Pelycodus.

In conclusion, Cantius has not been found to exhibit any features of resemblance to notharctids or adapids not occurring in the North American Omomyidae, and in view of numerous similarities to Omomys and Hemiacodon it is assigned to the latter family. The dental formula of Cantius is apparently more reduced than in Teilhardina, but evidence regarding the exact number of antemolar teeth remains inadequate.

8 A NEW EOCENE PRIMATE GENUS, CANTIUS

Cantius eppsi (Cooper) (PL i)

1932. Protoadapis eppsi Cooper, p. 461, pi. n, figs. 2, 3.

HOLOTYPE. Right ramus of mandible with P3-M3 and partial alveolar borders of I3-P2, B.M.N.H., M-I3773.

MATERIAL. B.M.N.H., M-I3773 (Holotype), B.M.N.H., M-I5I45, maxilla with P3-M3; B.M.N.H., M-i5i47#, mandibular fragment with Mj-Mg ; and B.M.N.H., M-I5I47&, mandibular fragment with M2_3.

HORIZON AND LOCALITY. Blackheath Beds (Sparnacian) ; Abbey Wood, one and three-quarter miles east of Woolwich, Kent.1

DESCRIPTION. Lower dentition: Dental formula: 2(?).i.3(?).3. One small incisor alveolus, followed by a much larger canine alveolus, narrow anteroposteriorly and broad buccolingually. If only one premolar was present anterior to P3 it may have been two-rooted. Two-rooted P3 with crown lower than P4 and lacking distinct para- and metaconids. Para- and metaconids well developed on P4, connected to protoconid by crests ; well-defined central crest on talonid, running posteriorly along mid-line of tooth from protoconid and with small posterior cuspule ; P4 not molar- ized. Trigonid of Mx large, with three well-separated cusps ; paraconid and metaconid joined to protoconid by low ridges ; talonid much larger than trigonid with distinct ento- and hypoconid, small hypoconulid present on slope of posterior crest of hypo- conid. Outline of M2 (crown view) more nearly circular than that of Mx, as in Ourayia, Hoanghonius, etc. Mg trigonid broad transversely, narrower anteroposteriorly, with more closely approximated paraconid and metaconid than Mj. Paraconid and metaconid of M3 trigonid either coalesced as a single cusp (M-I3773) or closely approximated (M-i5i47# and 6).

Upper dentition : B.M.N.H., M-I5I45 : P3~4 with slight constriction between protocone and outer cusp. P4 with small anterior cuspule, as in Hemiacodon. M2, M1, M3 ; no mesostyle or distinct hypocone on upper molars ; antero-internal base of molar protocone projecting most mesiad ; nannopithex-fold present on posterior slope of M1 and M2 ; paraconule and metaconule present on M1"3.

II. REVISION OF THE SPECIES OF PROTOADAPIS LEMOINE

History of Study

Preparation of the foregoing section on the British early Eocene primate Cantius necessitated investigation of all the available material of Protoadapis. It soon became clear that species of this genus were much in need of revision.

Unfortunately Stehlin's discussion of members of Protoadapis (1912 : 1284-1286) intruded some taxonomic confusion, as well as a misspelling of the generic name ; this was largely corrected by Teilhard (1921 : 66, 67, 88-91) but Stehlin's views, and additional misconceptions of dating quoted by Osborn (1890 : 55) have continued to

1 Dr. G. G. Simpson of Harvard University has suggested in a personal communication that the species of Hyracotherium from Abbey Wood indicate an earliest Eocene age for this fauna. This is also indicated by an M3 of Coryphodon from the same locality figured by Cooper (1932 : 459).

A NEW EOCENE PRIMATE GENUS, CANTIUS

Measurements (in mm.) of Cantius eppsi (Cooper) (All specimens in the British Museum of Natural History)

Mandible :

Depth of jaw beneath M2 Anteroposterior length of P3-M3 Anteroposterior length of Mx_3 Anteroposterior length of M2~3 Anteroposterior diameter of P3

Transverse diameter

(trigonid)

(talonid)

M2 M,

M2 M3

M!

M2 M,

Maxilla : M-I5I45 Anteroposterior diameter of P3

Anteroposterior diameter of P3

P4

M1 M2 M3

M-I3773

6-7 17-2 11-4

8-1

2-8

3'3 3-6 3-6 4'5

1-8 2-3 2-5 3'3 3'0

2-8

3'i 2-4

15-0

3-6

3'7

8-0

3-6 3'7 4'3

2-3 3-0 2-9 2-8 3'0 2'4

(Transverse diameter) 3'2 3-8 4'7 5'4 4'3

3-8 4'4

affect the literature on this primate. These errors were largely reproduced by Hill (1953 : 482-487).

Further complications derive from the observation, made during a recent visit to the Halle /Wittenburg Geological and Paleontological Institute, that the holotypes of two Eocene Primates, " Europolemur " klatti and " Megatarsius obeli " described by Weigelt (1933) can be assigned with confidence to Protoadapis. As it was not possible for Weigelt (1933) to make direct comparisons with previously described fossil Primates some specific and generic assignments which might have been recog- nized for the Geiseltal species were not noted by him. In fact, at that time Weigelt probably could not have determined his two new genera as upper dentitions and skulls of Protoadapis, since the associated upper and lower dentition, G.P.I.H. 4310, discussed below, had not then been discovered.

The assumption that species of this genus occur in the French Paleocene of Cernay and Rilly dates from an erroneous citation in Lemoine & Aumonier (1880 : 611) as stated by Teilhard (1921). * However, this misapprehension was repeated in Hill

1 Lemoine & Aumonier list a species of this genus, P. copei, as occurring in the Cernay Paleocene. It was not figured or described and is now lost, probably because Lemoine later referred the specimen to a different genus and species, not Protoadapis.

io A NEW EOCENE PRIMATE GENUS, CANTIUS

(1953 : 483). Lemoine later stated (1891 : 28) that this genus is restricted to the Eocene. D. E. Russell who is currently revising the French Paleocene faunas, informs me that it does not occur at Cernay. The recognition of several specimens of Protoadapis from the Middle Eocene Brown Coals of the Geiseltal, Germany, now in the collections at Halle, serves to date the earlier members of this genus better than the rather scanty and poorly associated Cuisian fauna with which the French specimens of Protoadapis curvicuspidens and " Protoadapis recticuspidens " were recovered.

A further error in the literature on this genus is its recorded occurrence in the Belgian Eocene deposits (Hill, 1953:483). There is no real evidence for such a record, but a specimen of Protoadapis from the Quercy phosphorites of south-central France was, at the time of Teilhard's writing, in a private collection at Louvain and his reference to it may have led to this confusion of range.

All the materials of this genus discussed by Lemoine, Stehlin, and Teilhard, as well as the specimens at Halle, belong (after the removal of " Protoadapis " eppsi) to no more than three species. Protoadapis recticuspidens Lemoine, 1878, is based (in spite of published remarks to the contrary) on a single specimen in which the teeth are so worn that only a few characters of M3 can be determined. This tooth, and the mandible, now in the Paris Museum, are distinctly smaller than are those of Protoadapis curvicuspidens (here designated as the type species of the genus) and it may not belong to Protoadapis. I would prefer to regard Protoadapis recticuspidens as a nomen vanum.

As Teilhard stressed, the specimen called Protiadapis recticuspidens by Stehlin (1912, fig. 278) is actually P. curvicuspidens, the holotype of which is now in the Museum National d'Histoire Naturelle in Paris. It is on the basis of this specimen that the genus Protoadapis was first defined.

TAXONOMIC REVISION

Genus PROTOADAPIS Lemoine

(Text-fig, i)

TYPE SPECIES. Protoadapis curvicuspidens Lemoine (1878). (Unnumbered holo- type and two other specimens in National Museum of Natural History, Paris.)

AMENDED DIAGNOSIS. Size : somewhat larger than Adapis parisiensis ; lower dental formula : i?.i.3.3. incisors missing in type but one or more alveoli appear to be present in other specimens ; canine large (alveolus) ; Pt absent, replaced by diastema ; P2 short with single pointed cusp, and with two obliquely situated roots, the anterior located more buccally. P3 distinctly larger, much higher and more pointed than P2 with nearly vertical anterior margin, no distinct paraconid or metaconid ; P4 lower than P3 (unlike Cantius) lacking paraconid, but with well-defined metaconid and talonid possessing central ridge ; molar paraconids reduced, but extending much more lingually than in Adapis, less so than in Cantius. Mj and M^ with small hypoconulid on posterior hypoconid crest ; M3 hypoconulid making up a distinct lobe ; length from P4 to M3 — 22 mm., depth of horizontal ramus beneath M2 from io to 12 mm.

A NEW EOCENE PRIMATE GENUS, CANTIUS n

DISCUSSION. Two French species of this genus are accepted here as valid, Proto- adapis curvicuspidens collected in Paris Basin deposits, perhaps of Cuisian age, and Protoadapis angustidens (Filhol, 1888) from the Quercy phosphorites (see Text-fig, i). Protoadapis brachyrhynchus Stehlin (1912) is clearly a synonym of the latter species, as Teilhard (1921 : 97) concluded. A third species, Protoadapis raabi, from the Middle Eocene Brown Coals of the Geiseltal, Germany, is slightly smaller than

COMPARISONS OF MANDIBLES OF Protoadapis species A (ALL X 2 APPROX., INTERNAL ASPECT)

Diagram of Protoadapis angustidens from ilhard (1921, pl.4. fig. 12 reversed)

Protoadapis curvicuspidens from Teilhard (1921, pl.3, fig.5)

GEOL. 7, I.

Protoadapis curvicuspidens from Stehlin (1912, fig. 288)

FIG. i. Species of Protoadapis Lemoine from French deposits.

i§§

12 A NEW EOCENE PRIMATE GENUS, CANTIUS

P. curvicuspidens but does not differ greatly from it otherwise, in so far as these two species can be compared. Better materials may prove that the latter two " species " intergrade but pending such an eventuality, it is advisable to retain a separate species for the Geiseltal finds.

SPECIFIC DIAGNOSES. Teilhard (1921) has published full descriptions of the two species of this genus from the French Eocene and consequently they will not be separately diagnosed here.1

Protoadapis klatti (Weigelt)

(Pis. 2, 3)

1933. Europolemur klatti Weigelt, p. 123, pi. 4, fig. 5 ; pi. 6, fig. 4. 1933. Megatarsius obeli Weigelt, p. 141, pi. 4, fig. 4 ; pi. 6, figs. 1-3.

MATERIAL. In addition to the holotypes of " Europolemur " klatti and " Mega- tarsius obeli " (No. 4234) ; numbers 4238, 4258, 4280, 4292 and 4310 of the collections of the Geological and Paleontological Institute of the University of Halle /Wittenburg are referable to this species. Some of these specimens were regarded by Heller (1930) as belonging to Adapis, but this genus does not occur in the Geiseltal fauna.

DIAGNOSIS. A medium-sized primate — apparently about the size of Pronycticebus

2 . 1 . "3 . "3

or the Recent Potto, Perodicticus. Dental formula : .r-1— — '- — ; anterior lower incisor

?l. 1.3.3 not known (if present), I3 procumbent and spatulate ; C long and pointed with

slightly developed posterior shelf — appearance about as in Notharctus, £ followed by diastema ; P2 two-rooted with simple pointed crown and posterior heel, lacking metaconid and protoconid ; P3 much higher than P2 and P4 and lacking protoconid ; P4-M3 as in Protoadapis curvicuspidens but smaller, Mx and M2 with distinct hypo- conulid on posterior slope of hypocone, M3 hypoconulid and entoconid large.

I2 larger than I3, spatulate with crown anteromedially directed and somewhat procumbent ; I3 small and simple, may be separated from C by a diastema ; C much larger and longer than in Adapis, furrowed along its external face by anterior and posterior vertical grooves and followed by a diastema ; P2 less than half as large as P3, and with small protocone (two rooted) ; P3 and P4 with single ectoloph and large protocone ; M1 lacking mesostyle and metaconule, but with distinct para- conule and prominent internal and external cingula, internal cingulum with large hypocone, basal cingulum sometimes incomplete across internal face of protocone ; M2 slightly larger than M1 with more continuous lingual cingulum and larger hypo- cone ; M3 smaller than JVF-M2, lacking a distinct hypocone, but with pronounced internal cingulum.

DISCUSSION. " Two " undescribed specimens in the Halle collection form a valuable basis for the clarification of the dental structure of Protoadapis. One of these G.P.I.H. 4310, from the Leonhardt Coal Mine (the locality of " Europolemur ") includes the left P4 through M3, the right M3 an associated right lower canine and M1"3 (M1"2 somewhat damaged) see PI. ^e,f. The second specimen, G.P.I.H. 4258 (PI. 2), crushed facial region with attached lower jaw fragment of the left side with I2 through P3

1 Protoadapis angustidens is larger and occurs later in time than P. curvicuspidens.

A NEW EOCENE PRIMATE GENUS, CANTIUS 13

and I3 through P3 was also collected from Leonhardt Mine. The specimen card of No. 4310 states that these teeth probably belong to the same individual as No. 4258, and this association is reinforced by similarity of colour, wear, matrix, and the fact that the two specimens do not share any overlapping parts, which would rule out such a possibility. In any event, both are referable to Protoadapis and together they preserve almost the entire dentition intact. Dental comparisons indicate that the skull of " Europolemur " klatti belongs to the same species as the foregoing specimens and is therefore a synonym of Protoadapis. The holotype of " E." klatti (apparently lost during the last war) has upper molars of the same size and conforma- tion as those of G.P.I.H. 4310 (judging from Weigelt's published information) and in so far as these two finds can be compared, there is no basis for a specific distinction. Teilhard (1921, pi. 3, fig. 6) illustrated an upper left molar which he suggested might be of P. curvicuspidens ; this is confirmed by the Halle specimens. Because of crush- ing, measurements on Brown Coal fossil Primates, other than on teeth, are not very reliable and thus have reduced value when drawing taxonomic distinctions. However, the length of P4-M3 series of Protoadapis klatti is about 15 mm. in the type and the length of P4-M3 in G.P.I.H. 4310 is about 17*2 mm. Similar measurements for Cantius eppsi are 14' 2 and 15*1 mm. respectively.

Regarding the teeth of " Megatarsius obeli " from the Cecilia Coal Mine (locality Leichenfeld II), as Weigelt noted (1933 : 142) : " die Beschaffenheit der Kronen 1st eigenartig stumpf , als wenn die oberste Schimelzchicht fehlte . . . ".

There is no doubt that this condition is due to post-mortem chemical absorption of the enamel and some of the dentine of the canine and P4 through M3 of the right side (all of the dentition that remains in " Megatarsius "). This sort of erosion of fossil teeth is quite common in early Cenozoic mammals. Neither Heller (1930) J nor Weigelt (1933) appear to have taken into account the fact that many of the Geiseltal Primates have lost almost all significant dental characters in this way. Such erosion also explains the extraordinary appearance of the canine of " Megatarsius " figured by Weigelt (1933, pi. 6, fig. i). In this tooth, the enamel and much of the dentine of the crown has been removed and there has also been erosion around the base of the tooth. The odd basal cingulum and the whole appearance of the tooth is unreal misleading. In " Megatarsius ", G.P.I.H. 4234, the upper dental formula is the same as in G.P.I.H. 4258-5310, Protoadapis. Furthermore, the eroded crowns of M1 and M2 show metaconule and mesostyle absent, but paraconule present, and allowing for the reduction in size caused by enamel erosion, M1"3 of " Megatarsius " are of appropriate size for Protoadapis klatti. For the writer, no doubt remains that " Megatarsius " is referable to P. klatti. In any case, G.P.I.H. 4234 is not adequate as a type specimen, and if not Protoadapis would be a nomen vanum.

Weigelt's discussion of the skulls of " Europolemur " and " Megatarsius " describes adequately these much damaged specimens. In overall morphology the skull of Protoadapis is more like that of Pronycticebus than of Adapis. With Pronycticebus,

1 Heller's holotype of Adapis minimus is an indeterminate specimen for the same reason, all of the enamel having been removed by chemical solution.

i4 A NEW EOCENE PRIMATE GENUS, CANTIUS

it shares a comparatively shorter rostrum, larger orbits, more slender zygoma, P4 with a single outer cusp and two-rooted P2, but differs in having lost P i/i. " Mega- tarsius " has a broad interorbital septum about i cm. wide and resembles that of Pronycticebus in the disposition of the medial end of the supraorbital margin. On the antero-dorsal face of this skull between the temporal crests is a broad and slightly depressed area. The temporal ridges converge to the mid-line about 2 '25 cm. behind the posterior end of the nasals. Conformation and extent of the nasals can be deter- mined in G.P.I. H. 4234. These bones are slightly expanded posteriorly as in Pronycti- cebus. The orbital region is much crushed and, consequently, the lacrymal foramen cannot be located, but fragments suggest that the post-orbital bar was more slender than in Adapis.

Relationships of Protoadapis

Now that both the upper and lower dentitions and something of the skull are known in Protoadapis, it takes a more significant position in early Primate history. Placement of this genus as a typical lemuroid primate seems beyond doubt, and in fact it is the only Old World early Cenozoic form which has the same dental formula as any of the living lemuroids, although it lacks the specialized tooth comb below which is typical of the latter taxon. Being older, and yet having a more reduced dental formula, it cannot be near the lines which gave rise to such Eocene lemuroids as Adapis, Pronycticebus and Notharctus. Perhaps its greatest similarities are with Pelycodus and Pronycticebus which, however, retain P I/I. In Pelycodus the manner of hypocone formation may also be different. Some specimens of Pelycodus, for instance A.M.N.H. 15022 (see Gregory, 1920, pi. 35), appear to have an incipient hypocone on the basal cingulum and at the same time another " pseudohypocone " developing from the nannopithex-fold on the posterior slope of the protocone. In the line leading to Notharctus the hypocone derived from the basal cingulum is suppressed, while in Protoadapis the nannopithex-fold is absent. The nearest known upper molar morphology that could give rise to both these patterns is that of Cantius but this form is too late to be ancestral to Pelycodus and its dentition too generalized for classification with the adapids. As suggested by Teilhard (1921), Simpson (1940), and others, Protoadapis shares with the North American notharctids many of the features which distinguish the latter group from the Adapidae. The upper dentitions and the anterior teeth preserved at Halle add somewhat to this conclusion, but in several respects this primate tends to link adapids and notharctids as Cantius links the omomyids with the latter families. In view of dental similarities with Caenopithecus and Pronycticebus, together with its European provenance, Protoadapis is here referred to the Adapidae.

III. NOTES ON PRONYCTICEBUS GAUDRYI GRANDIDIER

(Text-fig. 2)

The unique skull and mandibular fragment of Pronycticebus was discovered in 1893 and reported, in the original studies of Grandidier (1904, 1905), to be of Bar- tonian, late Eocene age, from Memerlein-le-Quercy in south-central France. The Abbe Rene Lavocat has suggested in a personal communication to the writer that

A NEW EOCENE PRIMATE GENUS, CANTIUS 15

judging from his studies of mammals of Oligocene provenance, there is a similarity in the colour of bone and matrix of this specimen to those of the European Oligocene. This interesting observation implies, at least, that Pronycticebus may be from the latest levels of the Quercy caves. If so, it could be of Stampian Oligocene provincial age.

Pronycticebus has long been a difficult form to assess taxonomically, due in part to the lack of specialization of the teeth and the presumed absence of a post-orbital bar. Grandidier originally suggested affinities with the living lorisiform Primate Nycticebus, hence its generic name. This view has some merit. Subsequently Gregory (1920) and others held that the species has tarsioid affinities. This conclusion appears to have been based largely on the brachycephaly of the skull (considerably more pro- nounced that in Adapis or Notharctus) and which, at the time of Gregory's writing, was rivalled in degree, among Eocene Primates, only by Necrolemur skulls (also from Quercy) and by a fragmentary skull, lacking dentition, from the Middle Eocene of North America described by Granger & Gregory (1917) as " Aphanolemur gibbosus ".

Gazin, in a revision of the Middle and Upper Eocene Primates of North America (1958), has shown that Aphanolemur is a synonym of Smilodectes. Several specimens figured by him indicate that expansion of the brain case in the latter primate (appar- ently closely related to Notharctus) has reached about the same level as in Pronycti- cebus. Skulls of Smilodectes, and to a lesser extent of Notharctus, demonstrate, therefore, that the degree of brain expansion which occurred in Pronycticebus was not unique among Eocene lemuroids. Protoadapis, judging from the crushed skulls at Halle, also had a rather large brain.

On other grounds, Le Gros Clark's careful study (1934) of the cranial anatomy of Pronycticebus has already demonstrated that this genus is not a tarsioid, a position recently re-affirmed by Piveteau (1957 : 55, 56).

Re-examination of the Evidence Orbital Region

It is, perhaps, an amusing commentary on the nature of appraisal of fossil speci- mens that the zygomatic arch of the one known skull of Pronycticebus can be said to have been " evolving " almost continuously since Grandidier 's original studies on this primate in 1904 and 1905. Apparently some time before the original description, the zygomatic arch was buried in a thick layer of plaster of Paris, which closely resembles the colour of the original bone. In 1934 Le Gros Clark remarked that the zygoma was not quite as broad as is indicated in Grandidier's illustrations and figured a narrower arch. Piveteau's plate (1957 : 61) shows a still more slender arch. In the same year, the writer was able to remove most of the remaining plaster which exposed a yet more gracile arch and the very distinct base of a post-orbital process (Text-fig. 2). Furthermore, the region of the frontal attachment of the post-orbital bar shows distinct fractures on both sides of the skull, where the bar has been broken off. The cross-sectional extent of this area is shown by hatching in Text-fig. 2. One can clearly distinguish the broken surface, and although this area of attachment is not very extensive in the vertical dimension, this correlates well the slender zygoma,

16

A NEW EOCENE PRIMATE GENUS, CANTIUS

FIG. 2. Dorsal and lateral views of the skull of Pronycticebus gaudryi (Holotype), Hatching indicates broken surfaces, stipple missing parts. In dorsal view, right side restored from left.

A NEW EOCENE PRIMATE GENUS, CANTIUS 17

found under the plaster, and with the much enlarged orbit indicated by the remaining median part of the orbital margin.1 Living and fossil Primates with comparatively large orbits often have a slender post-orbital bar and a thin and flaring zygoma, as in Galago and Necrolemur. In fact, in some Galago species, the temporal base of the post-orbital bar in cross-sectional area is less extensive (when compared to total skull size) than is this area in Pronycticebus.

In view of the observed presence in Pronycticebus of both a frontal and a zygomatic base for the post-orbital bar, the large brain compared to Adapis, the complete absence of any evidence that other primates of the grade of advance seen in Pronycti- cebus lack the post-orbital bar, and the suggestion that enlarged orbits do sometimes correlate with relatively small frontal areas of attachment for the bar, no basis now remains for thinking that the bar was not continuous. Text-fig. 2 presents a conjec- tural restoration of its position.

Le Gros Clark (1934 : 20-27) noted most of the observable characters in the skull of Pronycticebus and discussed occurrences of many of these features in other Primates. The numerous new fossil primate specimens, which have been discovered or restudied since that time justify further comparison of some of these structures. Contrary to the current assumption Pronycticebus gaudryi is not a conservative form. With existence of a post-orbital bar in this species established, little remains to be seen in it that is particularly primitive for an Eocene primate. In fact, the expansion of the brain case, the large, forward-directed eyes and the short rostrum are all features that have been considered " advanced ".

Location of the lachrymal foramen, together with part of the lachrymal bone, outside the orbit in Pronycticebus was suggested as a difference from Adapis by Le Gros Clark (1934). However, a specimen of Adapis magnus, P U. 11481, indicates that in this species the position of the foramen and forward extension of the lachrymal may sometimes be about as in Pronycticebus. In Malagasy lemurs the lachrymal foramen typically lies further outside the orbit than in the foregoing, while in living lorisines, and the potto in particular, the position of foramen and lachrymal is about as in Pronycticebus, except for the smaller size of the lachrymal itself. Necrolemur (M.C.Z. 1179) and Tarsius have also a facial location of this foramen, but in Smilodectes , Notharctus and most platyrrhines this foramen clearly lies within the anterior orbital margin, as in pongids and man. In this character it would seem that Adapis and Pronycticebus approach more closely the living lemuroids than they do members of the Notharctidae and Anthropoidea. Forsyth Major (1901 : 151) concluded that the primitive condition for Primates is to lack a great facial expansion of the lachrymal. Shape and position of the foramen and lachrymal in Pronycticebus appear to be equivocal in relating it either to living lemurids or lorisids.

Rostrum

The comparatively foreshortened face of this primate is evident from the parts preserved. A vertical position of the premaxillo-maxillary suture (as well as the anterior recurving of the alveolar border around the canines) indicates that the missing

1Relative to skull size Pronycticebus has larger orbits than most, if not all, other early Tertiary Primates. This may indicate nocturnal habits.

i8 A NEW EOCENE PRIMATE GENUS, CANTIUS

anterior tip of the skull can hardly have been much longer than the conjectural reconstruction shown in Text-fig. 2. The sharp constriction in transverse diameter of the rostrum immediately posterior to the canines in Pronycticebus is not as distinct in living lemurs and is absent in Adapis. However, this feature can be seen in Loris and Nycticebus, and is one of the reasons why this skull is reminiscent of that of Nycticebus coucang.

Dorsal Aspect of Skull

Cleaning of the skull has revealed sutures on the top of the brain case more clearly, and allows further comparison of this aspect of the skull in Pronycticebus with that of Adapis. Unlike Adapis, in Pronycticebus the posterior margins of the f rentals extend on to the anterior part of the brain case. A sinus canal, near the posterior extremity of the parietal, is single in Pronycticebus, but in Adapis parisiensis it is multiple, as noted by Le Gros Clark (1934 : 22) and indicated by Stehlin's figures (1912). A large size for this canal has been said to be a primitive feature. After cleaning, sutures can be determined in Pronycticebus delimiting paired interparietals and (posterior to the sinus canal) small accessory ossicles (see Text-fig. 2). These bones have not been reported as occurring in Adapis. Taken as a whole the dorsal aspect of the brain case of Adapis does not closely resemble that of Pronycticebus. Such distinctions suggest that by the Middle or Late Eocene (the exact time range for both forms is uncertain) these two lemuroids had already diverged considerably. Such an assumption is reinforced by distinctions in other skull components, discussed above, such as the different shape of the muzzle, divergent character of the dentition, and difference in position and size of the orbits in these two Primates of the Quercy phosphorites. At present, it is probably better to retain them in the same family, as has been done by Hill (1953) and Piveteau (1957). Nevertheless, Pronycticebus and Adapis are as distinct morphologically as forms from the North American Eocene currently placed in different families, for example the notharctid, Pelycodus, and omomyid, Ourayia see Simons (1961^:5).

Apart from the construction of the inside of the auditory bulla the basicranium of Pronycticebus was fully described by Le Gros Clark (1934). It will not be reconsidered in detail here. A possible alternative for an identification made by him (1934 : fig. 3) is that the foramen indicated as the hypoglossal canal may be the inferior petrous sinus.

On obtaining permission to examine the interior of the auditory bulla it was determined that the ectotympanic is not tubular, thus completely confirming, in this regard, Le Gros Clark's thesis that this primate is not a tarsioid. It is noteworthy that the annulus lies very near the external auditory meatus and, unless it has been displaced, appears to be fused with the bulla wall in its posterior third, just internal to the posterior rim of the external meatus. From this point the annulus arches inward and downward, so that its ascending anterior limb lies some distance from the antero-lateral wall of the bulla. Near the ventral extremity of the ring (and external to it) is a shelf on the lateral bulla wall for the support of the annulus membrane. Compared to that of Adapis this shelf is quite small. Hill (1953 : 113) figures a dissection of the auditory bulla of Loris tardigradus which indicates only

A NEW EOCENE PRIMATE GENUS, CANTIUS 19

slightly greater reduction of the annulus. The position of the tympanic ring in Pronycticebus, close to the external meatus, is an additional indication that Grandidier may have been nearer the truth than has sometimes been thought, when he suggested an affinity between this species and the modern lorises.

Dentition

It was principally because of the somewhat enlarged brain and generalized charac- ters of the dentition (resembling teeth of Anchomomys a supposed tarsioid), that such students as Stehlin (1916 : 1422), Gregory (1922) and Abel (1931 : 186) referred this primate to the tarsioids. Founding his conclusions principally on characters of the skull Le Gros Clark demonstrated that this primate cannot be considered a tarsioid. However, it may not have been sufficiently stressed that the dentition also, although unspecialized, is not Tarsius-like. Some principal reasons why this dentition does not indicate tarsioid relationships are as follows :

The cross-sectional area of the upper canine base is considerably greater relative to adjacent teeth than it is in Tarsius while in necrolemurines the upper canine is even smaller proportionately than in Tarsius. Tarsiids, with the possible exception of Nannopithex, lack the P1 present in Pronycticebus. The latter primate, like Adapis, Protoadapis, Anchomomys and Progalago, has two-rooted second premolars above and below, while in tarsiines, these teeth are always single-rooted. In configuration of the remaining teeth Pronycticebus closely resembles Protoadapis, but differs from it dentally in having a less well-developed lingual cingulum on the upper molar protocone, and a more reduced M2_3 paraconid. However, these are rather slight distinctions, known to be variable in other primate species.1 Otherwise, these two forms agree in such features as the absence of mesostyles, and of a distinct hypocone on M3 (although it is well developed on M1 and M2). Also, they are closely similar in proportion and size. It is just possible that better specimens might even show that species of these two types of Primates are not separable generically. Unlike tarsioids, Pronycticebus has, as Simpson (1940 : 202) remarks (with reference to Caenopithecus) " open trigonids and the peculiar mode of paraconid reduction so characteristic of Adapis and its close allies and unknown among any forms of really probable tarsioid affinities ".

Cranial Proportions

A logarithm of ratio diagram (Text-fig. 3) indicates graphically the close similarity in linear proportions between Pronycticebus and Nycticebus and in contrast to those of an early Cenozoic lemuroid species Adapis magnus? and a Recent Malagasy lemur.2

1 Even in Protoadapis, as is indicated by isolated upper molars from the Geiseltal coals at Halle, the lingual protocone cingulum of the upper molars is sometimes incomplete, as it also is in Pronycticebus.

2 Measurements indicated in Text-fig. 4 are as follows : (i) Transverse diameter from mid-line of skull to greatest flare of zygomatic arch. (2) Length of skull, from posterior margin of canine to anterior margin of foramen magnum. (3) Length of skull from posterior margin of canine to posterior extremity of skull. (4) Length of dentition from anterior face of canine to posterior edge of M3. (5) Greatest transverse width of dentition. (6) Greatest transverse diameter of the cranium. (7) Least post-orbital diameter of skull. (8) Length from posterior margin of the canine to end of hard palate. (9) Length from anterior margin of canine to point of least post-orbital diameter. (10) Length from point of least post-orbital diameter to posterior tip of skull, (n) Greatest diameter of orbit from base of post-orbital bar to opposite rostral orbital margin. (12) Greatest transverse diameter across auditory bullae. (13) Greatest transverse diameter across canines. (14) Least transverse diameter of muzzle across upper second premolars.

20 A NEW EOCENE PRIMATE GENUS, CANTIUS

The major differences between Nycticebus and Pronycticebus are in plots 4, 7, and 8. Measurement number 4, the length of the upper teeth might be expected to be less in Nycticebus as its dental formula is more reduced, and the same would apply to measurement number 8, the approximate length ol the hard palate. Measurement

Pronycticebus Nycticebus

2 3

4

5 6 7 8 9 10 II 12 13 14

L -.40

Ada pis (standard) fLemur \

\

v

*"^"**^w&

\.

I I I I I I I I I I — I — I — I — I — I — I — I

-.35 -.30 -.25 r20 -.15 -,IO-:05 0 +.05 +.10 +.15 +.20 +.25 +.30 +.35 +.40 +.45

FIG. 3. Logarithm of ratio diagram comparing cranial proportions in four prosimians ; Adapis (standard). Mean, and extremes of range are indicated for a sample of ten Nycticebus coucang.

number 7, the least post-orbital diameter of the skull (much smaller in Pronycticebus) is a primitive feature, correlated with a comparatively unexpanded brain, and is common to all Eocene lemuroids. In the remaining measurements Pronycticebus falls within (or very close to) the range of size variation of a small sample of the living lorisid Nycticebus coucang (10 individuals) .

CONCLUSIONS

Perhaps all the above-mentioned similarities are due to parallelism produced by similar adaptations in Pronycticebus and lorises, but such a view appears to be rather

A NEW EOCENE PRIMATE GENUS, CANTIUS 21

strained. A more likely conclusion is that Pronycticebus does have some relationship to the radiation which produced extant Lorisiformes. Nevertheless, because of many primitive structures also shared with the contemporary Adapis and Protoadapis it seems best not to remove this genus from the Adapidae, at present.

IV. THE TAXONOMIC POSITION OF ANCHOMOMYS STEHLIN (1916)

(Text-fig. 4)

This rather small primate, originally described by Stehlin (1916) occurs in deposits ranging from early Lutetian to early Ludian age in Europe. Four species have been proposed, differing little in known parts except for size. Taxonomic placement of this genus has varied considerably. Abel (1931 : 175) and others considered it a tarsioid, but Simpson (1940 : 202) quite correctly pointed out that such an assignment was most improbable. Of European Eocene lemuriforms the closest dental resemblances to Anchomomys are to be seen in Pronycticebus and Caenopithecus, but because of a common simplicity in cusp pattern their similarities can, perhaps, be over-emphasized. In some respects these three genera also resemble Adapis, particularly in type of paraconid reduction, but all three differ from Adapis in having M3 hypoconulid much more distinctly set off as a separate lobe from the hypoconid. They also lack the bicusped ectoloph of P4 and continuous lingual upper molar cingula seen in Adapis.

For Anchomomys the closest dental resemblances appear to be with a Miocene lorisiform of Kenya, Progalago. In fact, in spite of the differences in time and place of occurrence of the species belonging to these two genera, some of the European Eocene forms, particularly Anchomomys quercyi, can hardly be distinguished generic- cally, on the basis of parts preserved, from Progalago dome. Species of these genera also overlap as far as size is concerned and similarities in the lower molars are particu- larly striking. Both exhibit reduced paraconids, well-developed entoconids, a large M3 hypoconulid, with remaining molar cusps of closely corresponding shape and situation relative to one another. Both these prosimians also display in the major molar cusps a fairly distinctive angular or pyramidal form.

The upper molars of Anchomomys are quite like those of Progalago although in some, but not all, species of Anchomomys the paraconule and metaconule are more distinctly developed. In Progalago dorae and Anchomomys quercyi the latter two cusps are absent, see Text-fig. 4. These two species are alike in having a subquadrate M1 with large hypocone, more triangular M2 with smaller hypocone and lack a distinct M3 hypocone, see Text-fig. 4 ; Le Gros Clark (1956, pi. i) and Stehlin (1916, figs. 327, 328, 332). Moreover, at least one specimen of Progalago dorae (Le Gros Clark & Thomas, 1952, pi. 3, fig. 9) shows that in this species the P2 was a much elongated and two-rooted tooth. If the same applies to the maxilla of Anchomomys quercyi figured by Stehlin, and shape of the anterior alveoli strongly indicates this possibility, then the upper dental formulae of both species are identical, at least from the canine posteriorly.

Perhaps the best preserved skull of Anchomomys is that of the unnumbered holotype of Anchomomys latidens (now in Paris) described by Teilhard (1921 : 13}

22 A NEW EOCENE PRIMATE GENUS, CANTIUS

from the Quercy phosphorites and identified as " Rossignol Collection 1893 : n ". The specimen is much broken and distorted, but careful preparation could probably expose more of the cranial anatomy. As in Pronycticebus and Progalago there is a single large infra-orbital foramen above P4. The anterior root of the zygoma appears to arise about M2, and through this anterior root opens to the rear a relatively large posterior infra-orbital canal. On the antero-dorsal surface posteriorly converging

FIG. 4. — Comparison of upper dentition in Anchomomys and Progalago. A. Progalago sp.. [Diagram after Le Gros Clark, 1956, pi. 4, fig. i.] Right maxilla, reversed, xy-5 approx. B. Anchomomys quercyi. [After Stehlin, 1916, fig. 332.] XJ'5 approx.

temporal ridges are evident, but the dorsal insertion of the post-orbital bar cannot be distinguished. Between these temporal ridges, there is a broad depression, appear- ing rather as does this area in Pronycticebus. An apparently distinctive feature of Anchomomys latidens is the character of the surface of the temporal bone which is covered by numerous minute foramina, a condition certainly not to be seen (to this extent, if at all) in Adapis or Necrolemur. At the back of this skull are well- developed nuchal crests. These are typical of Eocene Primates and their presence is consistent with the retention of similar strong ridges in this position in Progalago.

A NEW EOCENE PRIMATE GENUS, CANTIUS 23

Taxonomic Position

Stehlin (1912 : 1426) tended to favour the idea that Pronycticebus and Anchomomys have about the same relationship to the Galagidae [" Nycticebiden "] as Adapis has to the lemuriform lemurs, but remarked that until the position of the carotid foramen and situation of the extotympanic was revealed for one of these Primates their taxonomic position would remain uncertain. Now that the annulus of Pronycti- cebus is known to show a possible foreshadowing of the condition seen in lorisiform Primates, Stehlin's analysis is strengthened. The subsequent placement of these two genera among the tarsioids, proposed for Anchomomys by Teilhard (1921),, and for both Pronycticebus and Anchomomys by Gregory (1922) and Abel (1931) can now be seen to have marked a step backward in determination of their relation- ship to other prosimians.

Teilhard, although stressing tarsioid relationships for Anchomomys latidens, did however remark (1921 : 16) : " Tout au plus pourrait-on le rapprocher des Galago pour le developpment de 1'hypocone et la tendance a la molarisation de P 4 . . . ". This observation is important taxonomically because the fourth upper premolar in species of the genera Anchomomys, Progalago and Galago has an interesting similarity in basic plan, in addition to the other features of resemblance between these genera mentioned above. The view that these forms were tarsioids was rejected by Simpson (1940) after Le Gros Clark's study of the cranial anatomy of Pronycticebus, but since then their position among the non-tarsioid Prosimii has remained uncertain.

The very close dental relationship between Anchomomys and Progalago, and the similarities which the latter in turn has with living lorisoids reinforce the idea that this phylum can now be traced back with a fair degree of accuracy as far as the European Middle Eocene.

V. RELATIONSHIPS OF EARLY TERTIARY LEMUROID PRIMATES

The Concept of " Lemur vid " Primates

One objective of the research reported here and in Simons (1961) has been to determine whether tarsier-like and lemur-like Primates can be distinguished in the early Cenozoic. For at least one subfamily of this period, Necrolemurinae, a definite relationship with Tarsius is indicated. Most remaining Paleocene and Eocene Primates have (or should have) been termed " lemuroid " in the past. A great many fossil genera have consistently been classified as tarsioid when there is no basis, in known parts, for so doing. If one examines the better known lemuroid Primates they seem to be of four general kinds, as follows :

(i) Species on the border-line between Primates and Insectivora as these orders are currently understood, of the families :

Amphilemuridae

Microsyopidae

Apatemyidae

24 A NEW EOCENE PRIMATE GENUS, CANTIUS

(2) Specialized Primates of early extinction. Forms too specialized dentally to be near ancestral lines of later stocks :

Families :

Plesiadapidae

Carpolestidae

Anaptomorphidae [in part]

Paromomyidae [ — Phenacolemuridae, in part]

(3) Relatively generalized groups that could be near the ancestry of some living families, but which show no convincing evidence of having reached a tarsioid, or higher, grade of advance.

Families :

Adapidae Notharctidae

(4) Generalized Primates, possibly close to the stocks which gave rise to living groups, but which are not well enough known to indicate their grade of advance.

Omomyidae

perhaps some [paromomyids and anaptomorphids]

Past usage has roughly equated the term lemuroid with at least some members of each of the four groups of extinct families listed above. Such usage implies, however, that all these types can be assigned to the Lemuridae, which is not the case. On the other hand, it is surely valid to assume that the ancestral stocks of all the groups which have advanced beyond the lemur-like state (represented today by tupaiids and lemurids) went through such a level of advancement, and consequently their ancestors of the early Cenozoic can correctly be called lemuroid or lemur-like. Obviously then, among fossil forms that are distinctly lemuroid may be found ancestors of the more advanced Primates : tarsioids, and anthropoids. Some members of the above families do foreshadow tarsioids. For instance, Navajovius of the Tiff an- ian Paleocene of Colorado and Teilhardina of the Sparnacian Eocene of Belgium, both exhibit interesting dental resemblances to the European Middle Eocene tarsiid, Nannopithex, while the only skull with advanced (or tarsioid) features ever discovered in North America (Tetonius ; A.M.N.H. 4194) also possesses upper molars that, together with a general similarity of detail, share with those of Nannopithex an unusual feature, the nannopithex-fold. At present these four genera are assigned to three different families, viz.

Navajovius and Teilhardina . Omomyidae (Simpson, 1940 : 208) Nannopithex .... Tarsiidae (Simons, 1961 : 61) Tetonius . . . . Anaptomorphidae (Gazin, 1958 : 73)

Dental variation among these primates is not as great as their assignment to different families implies, being in most ways far less than seen in the Malagasy family Lemuridae. Yet, until better cranial remains are known for some omomyids, paro- momyids and anaptomorphids it will remain difficult to judge whether or not these

A NEW EOCENE PRIMATE GENUS, CANTIUS 25

groups show the same definite indications of tarsioid relationships in their osteology than they do in their dental anatomy. All these most interesting Primates fall within the fourth group listed on p. 24. In regard to the first three groups primatolo- gists are on safer ground, for they are either so primitive dentally that tarsioid relationships cannot be considered or they are known from skulls that show no convincing tarsioid features. In the broadest sense it appears reasonable to call these forms lemuroid, and it is with them that the following paragraphs will be concerned.

Border-line Primates A mphilemuridae

This family, proposed by Heller (1935) for the reception of Amphilemur eocaenicus from the Middle Eocene deposits of the Geiseltal, has recently been assigned to the Erinaceoidea (Insectivora) by McKenna (1960 : 58). To this subfamily McKenna also assigns, among others, the following North American Paleocene and Eocene genera : Entomolestes , Macrocranion and Sespedectes. As far as Primate classification is concerned, this procedure is not likely to improve the taxonomy of the genera involved, for the type of Amphilemur cannot be located at Halle, and if lost makes an unsatisfactory choice as the type genus of a subfamily known otherwise only in the New World, and to which it may not belong. Both Simpson (1945) and Hill (1953) refer Amphilemur to the Adapidae, incertae sedis. In its poorly-known state, now entirely dependent on Heller's text and figures, there is little basis for placing it elsewhere. In Adapis parisiensis the lower canine is often very small and otherwise the antemolar teeth exhibit gradual and nearly unbroken size-decreases from back to front, which is not unlike the size sequence of these lower teeth in Amphilemur and which shows that the same general kind of tooth proportions seen in Amphilermir can occur in a primate.

Microsyopidae

McKenna (1960 : 76) has re-defined this family so as to include the following genera : Microsyops, Craeseops and Cynodontomys. His view, that this family belongs among the Primates appears to have sound justification. He is of the opinion that the nearest affinities of the Microsyopidae, as re-defined by him, are with the more primitive plesiadapids of North America. Moreover, he remarks (1960 : 78, 79) while discussing Microsyopidae :

" Recently Hiirzeler (1948^, pp. 343-356) has described a new genus and species, Alsaticopithecus leemanni, from the Lutetian of Alsace, based on excellent dental material. The animal was placed in the Primates incertae sedis. Alsaticopithecus appears to me to be a microsyopid ... As Hiirzeler notes, the genus is indeed primatelike. Thus Alsaticopithecus has a bearing on the problem of microsyopid origins. The genus is an interesting extension of the known statigraphic and geographic range of microsyopids."

In view of this assignment of Alsaticopithecus, taken together with what is now known of microsyopid anatomy, including cranial material, soon to be reported on

26 A NEW EOCENE PRIMATE GENUS, CANTIUS

by McKenna, Hiirzeler's conjecture that this form has significant dental resemblances to Anthropoidea is no longer tenable.

Apatemyidae

The series of genera now assigned to this family were first clearly distinguished from plesiadapids by Jepsen (1934). Although they are retained provisionally in the order Primates by Gazin (1958), research on the basicranium reported by Hiirzeler (1949 : 485) indicates that this group is almost certainly not to be referred to the Primates, as the order is now defined. Notwithstanding this, the apatemyids may have had their origin in the same eutherian stock from which the Primates arose — a conclusion which is indicated principally by molar-pattern resemblances. They certainly have no close connection with Paleocene- Recent Primates and will not be considered further here.

Specialized Lines of Early Extinction

A number of divisions of the order of family and subfamily status, which became extinct before the end of the Eocene, exhibit such pronounced dental specializations that it is clear they could not be near the ancestry of any living Primate species. Of these, the carpolestids are the least well understood, but conformation of the fourth lower premolar alone (elongate and saw-like) removes them from consideration as ancestral to surviving lines. The same applies to plesiadapids, and to Phenacolemur1 because of the marked reduction of their anterior dentition. Even so, Plesiadapis is of interest because of its geographical distribution. Species of this genus are known from the late Paleocene of both Europe and North America. This occurrence demon- strates that climatic conditions as well as the requisite land-bridges, allowing not only other mammals but prosimians to communicate between these two continents then existed, and helps to explain the presence of omomyids, microsyopids and possi- bly other primate families, in both continents in the early Eocene.2

Among the plesiadapids, carpolestids, and paromomyids the cranial and post- cranial anatomy is poorly known except in two species of Plesiadapis. The limb bones of Plesiadapis studied by Simpson (and greatly amplified by undescribed specimens recently collected by Russell in the Cernay Paleocene deposits near Rheims in central France) are primitive, but can be spoken of as lemur-like. Russell (1960) briefly reported on a remarkably well-preserved skull of Plesiadapis from the Cernay region. This is the oldest primate skull yet to be described. The skull of Plesiadapis is very broad, flat, with a small brain-case, while the premaxillaries are enormously expanded and make up most of the muzzle. Elsewhere, among Primates such expanded premaxillaries occur only in the Madagascan lemur Daubentonia. However, a relationship with the latter is excluded by the presence in Plesiadapis, but not in Daubentonia, of a tubular ectotympanic element. Finally, it is clear that in Plesiadapis there is no post-orbital bar, nor any indication of post-orbital processes.

1 Here regarded as a paromomyid, following McKenna (1960 : 70).

2 Basically all living prosimians are tropical forest dwellers. Uniformitarian reasoning would suggest that their early Cenozoic forerunners were also warm-climate animals.

A NEW EOCENE PRIMATE GENUS, CANTIUS 27

From this feature of the Cernay Plesiadapis skull it must be concluded that the basal stock of the order lacked the post-orbital bar, although it occurs in all other undoubted Primates (for which this part of the skull is known) with the single exception of Anagale from the Oligocene of Mongolia.

The families Anaptomorphidae and Paromomyidae are known only from North America. In terms of present knowledge, they include the most likely candidates for a relationship with the rise of tarsioids and of surviving higher Primates, possibly by way of containing forms ancestral to the omomyids. Regrettably members of these families, with the exception of Tetonius, are known only from dentitions, and consequently, little can be said as to whether they are lemur-like or tarsier-like. The same is true for omomyids. Nevertheless, dental analogies suggest that some of the species referred to these families were at least transitional to the tarsioid grade and such an assumption is further indicated by the large, forward-directed orbits and expanded brain of Tetonius.

VI. REVISED CLASSIFICATION OF EUROPEAN EOCENE PRIMATES

Revisions included here, in Simons (1961), and in a number of other works published since Simpson (1945) now make it possible to assign taxonomically certain European early Cenozoic Primates formerly listed by Simpson as incertae sedis, as well as to transfer others for which a better placement can be supported. The most recent extensive treatment of these forms is by Hill (1953, 1955), but Hill's taxonomy is clearly synoptic and no revision of fossil prosimians is included in these works. The following section, therefore, attempts to bring the classification of the fossil Primates of Europe up to date.

Genera to be considered here are listed in Simpson (1945) as follows :

Plesiadapidae :

Megachiromyoides Weigelt, 1933. M. Eoc.; Germany. Adapidae incertae sedis :

Caenopithecus Riitimeyer, 1862. M. Eoc.; Switzerland. (?) PROSIMII of uncertain infraorder or family :

Ceciliolemur Weigelt, 1933. M. Eoc.; Germany. Europolemur Weigelt, 1933. M. Eoc.; Germany. Megatarsius Weigelt, 1933. M. Eoc.; Germany. Microtarsioides Weigelt, 1933. M. Eoc.; Germany.

Two additional Eocene Primates from Europe described by Hiirzeler (1946, 1947) are also discussed in the following pages.

Gesneropithex peyeri Hiirzeler, 1946. M. Eoc.; Switzerland. Alsaticopithecus leemanni Hiirzeler, 1947. M. Eoc.; Alsace.

Inasmuch as the European plesiadapids, and a specimen from the Walbeck Paleocene of Germany, referred to Phenacolemur by Weigelt (1947) but of uncertain generic and familial assignment are currently under study by others they are not discussed here in detail. These groups are, however, indicated in Text-chart I, in

28

A NEW EOCENE PRIMATE GENUS, CANTIUS

PALEOCENE	EOCENE
PROVINCIAL AGE	THANETIAN	SPARNACIAN INCL. EARLY YPRESIAN	CUISIAN EQUALS LATE YPRESIAN	LUTETIAN	BARTONIAN	LUOIAN
EARLY	LATE	EARLY	LATE
				_,^-	Necrolemur	Necrolemur	Necrolemur
			^"		"--		Microchoerus	Microchoerus
X	,,---'	ftilhordino	,'-	Nannopithex	Nannopithe*		Pseudolor/s Gesneropithex Anchomomys Adapts Protoadapis	Adopis
	Periconodon	> OMOMY	DAE
- Cantius
Anchomomys — Adapts Caenopithecus	Anchomomys Adapts Protoadapis	Anchomomys Adapts Protoadapis Pronycticebus
\	X V Chiromyoides
^•* ^	Protoadapis ^
>
N
*\_	Plesiadopis	Plesiadapis *	• PLESIAC	JAPIOAE
\ \ N X.		Plalychoerops	^
	Phenacolemur	">PAROMO	MYIDAE
\ \ X	***•.	J		Alsoticopithec	us > MICRO J	SYOPIDAE

CHART I

Temporal occurrence of early Cenozoic European primate genera indicating approximcte interrelationships. (* Occurrence in this horizon dubious.)

CHART i.

A NEW EOCENE PRIMATE GENUS, CANTIUS 29

which temporal occurrences and approximate interrelationships of all European early Tertiary Primates are shown.

Megachiromyoides

Since Megachiromyoides is frequently referred to in the literature as a primate, it should be emphasized that Stehlin & Schaub (1951 : 21) stated that it is a rodent, assignable to the genus Aeluravus. A recent examination, by the writer, of the holo- type of " Megachiromyoides " from the Geiseltal Brown Coals (described by Weigelt, 1933) has confirmed the view that this form cannot possibly be a plesiadapid.

Caenopithecus

This interesting primate from Middle Eocene (Lutetian) deposits near Egerkingen, Switzerland was originally described by Rutimeyer (1862). Stehlin (1916) discussed the species further and figured a mandible which shows only one incisor alveolus on either side. He stated that his material indicated the same lower dental formula as in Tarsius, and noted other advanced features including the loss of the first upper and lower premolars, and a short rostrum.

Corroboration of Simpson's placement (1940) of this primate among adapidscan be drawn from its similarities with the Lutetian species Protoadapis klatti. Principally Caenopithecus differs from Protoadapis in showing more reduced molar paraconids, in the possession of distinct mesostyles and in having less well-developed upper molar lingual cingulum. Protoadapis also exhibits a more distinct P3 protocone. In spite of these generic differences, however, Caenopithecus and Protoadapis are, in upper and lower dental conformation, in dental formula and in what is known of the skull, much closer to each other than either is to Adapis, but (in different ways) both exhibit some features of resemblance to a species of the latter genus.

Stehlin (1916 : 1319) remarked that knowledge then available of Caenopithecus lemuroides indicated affinities with Protoadapis and Pelycodus and this view has been strengthened by the better material of Protoadapis klatti now known. Protoadapis and Caenopithecus agree in possessing the following features, some of which are unknown among other European Eocene Primates : Long and large canines (above and below) — not very procumbent ; PI/I absent and replaced by diastema ; P3 higher than P4 ; metaconule of upper molars lacking but distinct paraconule present ; well-developed hypocones on M1"2 only ; upper molar cingula (labial and lingual) well defined and in some individuals continuous across lingual base of protocones ; similar proportions in lower molars.

Common possesssion of pronounced upper molar cingula, absence of a distinct Pa protocone and near identity in overall proportions of the lower molars between Caenopithecus and Adapis parisiensis, tend to link species of these two genera as well. Weigelt noted a slight mesostyle on the M2 of Protoadapis klatti (also in agree- ment with Caenopithecus} and expressed the view that his Brown Coal species was closer to Caenopithecus than to Adapis. Moreover, his illustration of the skull of P. klatti (1933, pi. 6, fig. 4) indicates a vertically deepened anterior base for the zygomatic arch, as in Caenopithecus lemuroides. One further similarity between

30 A NEW EOCENE PRIMATE GENUS, CANTIUS

these two types of Primates is the possible loss (reported for species of both genera) of all but one pair of lower incisors. Because of the low angle at which the anterior alveolar border of the mandible of Caenopithecus (Basel Eh. 733) from which this was deduced, is broken off, the possibility remains that there were more incisors below. In some specimens of Adapis parisiensis in the Paris Museum, where this margin is broken off in a similar way, the incisor alvoli are entirely missing. If these were the only known specimens of A . parisiensis its lower incisor formula would be equally uncertain. The exact number of lower incisor pairs in given Eocene primate species can seldom be stated categorically. Both Caenopithecus and Protoadapis could have had two pairs of these teeth, but present evidence is not adequate to prove that they did.

A further note of some interest regarding Caenopithecus , and the nature of true hypocones and pseudohypocones, is provided by a specimen of this primate at Basel (Eh. 727) which shows both kinds of hypocone formation in one individual. The retention of both of these patterns in this dentition suggests that a latency for producing pseudohypocones, as in the line leading to Notharctus as well as for true hypocone production in Adapis, probably existed in the ancestral adapid-notharctid stock.

Periconodon

The genus Periconodon was established by Stehlin (1916) for a species " helveticus " which had been assigned by Riitimeyer (1891 : 115) to the North American genus Pelycodus. Like most Caenopithecus materials the type of Periconodon helveticus came from Middle Eocene deposits near Egerkingen, Switzerland. Apparently no additional specimens referable to this genus have been discovered since Stehlin's discussion.1 The individual illustrated by Stehlin (1916, pi. 22 fig. 3), which preserves P3 and M1"2 shows a distinctive pericone on the antero-internal base of M1"2 proto- cones. Since a pericone sometimes occurs here in Omonys (see Gazin, 1958, pi. 6, figs. 3 4) but not elsewhere among early Tertiary Primates, and because omomyids are known to have been present in the European Eocene fauna, the provisional reference of Periconodon to this family seems advisable. Furthermore, the small size of the species and general conformation of the teeth does not suggest adapid or notharctid affinities.

Ceciliolemur and Microtarsioides

Ceciliolemur is now considered by Matthes (1957), and by others, to be an insecti- vore, primarily because it seems to have had dermal spines. Recent examination of the holotypes of Ceciliolemur, G.P.I.H. 4237, and of Microtarsioides, G.P.I.H. 4235, both from the Geiseltal Brown Coals of Cecilia mine, locality Leichenfeld II, indicates strongly that they belong to the same species. Cheek teeth do not survive in either specimen, so dental formula and affinities cannot be determined. Moreover, the

1 Heller (1930) and Weigelt (1933) both mention the presence of isolated upper molars of this Primate in the Geiseltal Brown Coals. These teeth do not belong to Periconodon, but are those of a larger Primate from which the enamel has been resorbed. What remains of the cusp bases suggests their reference to Protoadapis klatti.

A NEW EOCENE PRIMATE GENUS, CANTIUS 31

condition of bones and of eruption of lower teeth indicate that both are very young individuals, perhaps pre-natal. No basis remains for referring either of these speci- mens to the Primates. It is a remarkable accident of fossilization that either of these very delicate specimens were preserved, considering that the body excluding the tail, in both cases, is only about 4 cm. long. Locality data indicates recovery from the same place, and possibly they are from the same " litter ".

Europolemur and Megatarsius

As discussed above (pp. 13, 14) these primate genera are junior synonyms of Protoadapis.

A Isaticopithecus

The species A Isaticopithecus leemanni Hiirzeler (1947) can be assigned to the family Microsyopidae, as re-defined by McKenna (1960 : 76), see p. 25.

Gesneropithex

Gesneropithex peyeri Hiirzeler (1946) is based on a lower jaw containing P4_M2and one second upper molar collected in Ludian deposits near Bosgen, Switzerland. The lower teeth differ from Alsaticopithecus and resemble such adapids as Anchomo- mys, in that M1_2 lack distinct hypoconulids. Moreover, conformation of the upper second molar is within the general range of variability of species now assigned to the Adapidae. M2 is most similar in size and cusp pattern to those of Anchomomys latidens, but wear obscures some of its features. Anchomomys and Gesneropithex also agree in one rather unusual feature of M2 ; both have a strong anterior crest running from the metaconule to the metacone. Presence of an upper molar mesostyle in Gesnero- pithex is in agreement with Caenopithecus. It seems reasonable to assume that Gesneropithex peyeri can be referred to the Adapidae (s.s.).

REVISED CLASSIFICATION1

Order PRIMATES

Suborder PROSIMII

Family TARSIIDAE Gray, 1870

Subfamily NECROLEMURINAE Simpson, 1933

MICROCHOERUS Wood, 1844

Synonyms — Microchaerus Forbes, 1894

Necrolemur : Filhol, 1880 (in part)

Microchoerus erinaceus Wood, 1844 Microchoerus edwardsi (Filhol, 1880)

Synonym — Necrolemur edwardsi Filhol, 1880 Microchoerus ornatus Stehlin, 1916

1 Since a revision of the European plesiadapids is currently being undertaken by Russell at the Paris Museum they have been omitted from this classification.

32 A NEW EOCENE PRIMATE GENUS, CANTIUS

NECROLEMUR Filhol, 1873

Necrolemur antiquus Filhol, 1873 Necrolemur zitteli Schlosser, 1887

NANNOPITHEX Stehlin, 1916

Synonyms — Necrolemur Chantre & Gaillard, 1897

Pseudoloris : Weigelt, 1933 Nannopithex filholi (Chantre & Gaillard, 1897)

Synonyms — Necrolemur filholi Chantre & Gaillard, 1897

Nannopithex pollicaris Stehlin, 1916 Nannopithex raabi (Heller, 1930)

Synonyms — Pseudoloris abderhaldini Weigelt, 1933 Necrolemur raabi Heller, 1930

PSEUDOLORIS Stehlin, 1916

Synonym — Necrolemur : Filhil, 1889 Pseudoloris parvulus (Filhol, 1889)

Synonym — Necrolemur parvulus Filhol, 1889

Family OMOMYIDAE Gazin, 1958

TEILHARDINA Simpson, 1940

Synonym — Omomys Teilhard, 1927 Teilhardina belgica (Teilhard, 1927)

Synonym — Omomys belgicus Teilhard, 1927

CANTIUS nov. gen.

Synonym — Protoadapis : Cooper, 1932 Cantius eppsi (Cooper, 1932)

Synonym — Protoadapis eppsi Cooper, 1932

PERICONODON Stehlin, 1916

Synonym — Pelycodus Riitimeyer, 1891 Periconodon helveticus (Riitimeyer, 1891)

Synonym — Pelycodus helveticus Riitimeyer, 1891

Family ADAPIDAE Trouessart, 1879 ADAPTS Cuvier, 1822

Synonyms — Aphelotherium Gervais, 1848 Leptadapis Gervais, 1852 Palaeolemur Delfortrie, 1873

A NEW EOCENE PRIMATE GENUS, CANTIUS 33

Adapts parisiensis Blainville, I84I1 Adapts magnus Filhol, 1874 A da pis rutimeyeri Stehlin, 1912 Adapis prisons Stehlin, 1916 Adapis sciureus Stehlin, 1916

PROTOADAPIS Lemoine, 1891

Synonyms — Plesiadapis : Lemoine, 1878 (in part) Protadapis : Stehlin, 1912 Megatarsius Weigelt, 1933 Europolemur Weigelt, 1933 Protoadapis curvicuspidens2 Lemoine, 1878

Synonym — Protadapis recticuspidens : Stehlin 1912 (in part) Protoadapis angustidens (Filhol, 1888)

Synonyms — Adapis angustidens Filhol, 1888

Protadapis brachyrhynchus Stehlin, 1912 Protoadapis klatti (Weigelt, 1933)

Synonyms — Europolemur klatti Weigelt, 1933 Megatarsius obeli Weigelt, 1933

CAENOPITHECUS Riitimeyer, 1862

Caenopithecus lemur oides Riitimeyer, 1862

PRONYCTICEBUS Grandidier, 1904

Pronycticebus gaudryi Grandidier, 1904

ANCHOMOMYS Stehlin, 1916

Synonym — Caenopithecus : Riitimeyer, 1891 Anchomomys Pygmaeus (Riitimeyer, 1891) Anchomomys gaillardi Stehlin, 1916 Anchomomys quercyi Stehlin, 1916 Anchomomys latidens Teilhard, 1916

GESNEROPITHEX Hiirzeler, 1946 Gesneropithex peyeri Hiirzeler, 1946

Family MICROSYOPIDAE new sense, McKenna (1960)

ALSATICOPITHECUS Hiirzeler, 1947

Alsaticopithecus leemanni Hiirzeler, 1947

? Primates incertae sedis

AMPHILEMUR Heller, 1935

Amphilemur eocaenicus Heller, 1935

1 For numerous synonyms of the various species of Adapis, see Stehlin (1912, 1916).

2 Here designated as the type species of Protoadapis.

34 A NEW EOCENE PRIMATE GENUS, CANTIUS

VII. CONCLUSIONS

' The occurrence of a new omomyid prosimian genus, Cantius, from the English Sparnacian is reported on and its distinctions from the Middle Eocene genus Proto- adapis outlined. Assignment of this form to the Omomyidae reinforces the extension of the range of this family into the Old World suggested by a few previously described forms. Although additional resemblances to North American notharctids are noted for Protoadapis, it is referred to the Adapidae on the basis of its greater similarities with Caenopithecus and Pronycticebus. Preliminary evidence suggests that Notharctidae and Adapidae, as denned by Gazin (1958) may not actually be distinguishable, but solution of this problem requires additional comparative study.

Certain loris-like features of the genus Pronycticebus are pointed out. Just possibly, these can be interpreted as indicating the differentiation of the lorisiform prosimians from the general stock of the Adapidae (s.l.) . A high degree of dental similarity between an undoubted lorisoid prosimian, Progalago, of the early Miocene of Kenya, and the late Eocene European primate Anchomomys is stressed. These findings are in contrast to the widespread opinion that no close relationship of early Cenozoic with Recent prosimian families can be demonstrated, but is in line with the vertical taxonomic association of necrolemurines and tarsiines proposed by Simons (1961). However, zoogeographical and morphological considerations alone are sufficient to indicate that it would be unwise to regard any such relationships direct ancestor-descendant lineages.

A number of species previously regarded as incertae sedis are here re-assigned or removed from the order and the taxonomy of European Eocene Primates revised.

VIII. ACKNOWLEDGEMENTS

I should like to thank Dr. K. P. Oakley of the British Museum (Natural History), Dr. J.-P. Lehman of the National Museum of Natural History, Paris, and Drs. H.-W. Matthes and G. Krumbiegel of the Geological and Paleontological Institute of the Martin Luther University of Halle/Wittenburg for the opportunity to study and report on Eocene Primates in their respective collections. Thanks are also due to Dr. G. L. Jepsen of Princeton University, Sir Wilfrid Le Gros Clark, and to many others with whom this subject has been discussed. Figures were prepared by Miss Christine Court of Oxford University and Mrs. Margaret E. Freeman of New Haven, and early completion of the work facilitated by a grant from the Wenner-Gren Foundation for Anthropological Research.

IX. REFERENCES

ABEL, O. 1931. Die Stellung des Menschen im Rahmen der Wirbeltiere. 398 pp. Jena. BARNETT, C. H. & NAPIER, J. R. 1953. The rotatory mobility of the fibula in eutherian

mammals. /. Anat. Lond., 87 : 11-21. CHOW, MIN-CHEN. 1961. A New Tarsioid Primate from the Lushi Eocene, Honan. Verte-

brata Palasiatica, Peking, 5 : 1-5, 3 figs. CLARK, W. E. LE GROS. 1934. On tne skull structure of Pronycticebus gaudryi. Proc. Zool.

Soc. Lond., 1934 : 19-27, 3 figs.

— 1956. A Miocene lemuroid skull from East Africa. Fossil Mammals of Africa, 9, 6 pp. i pi. British Museum (Nat. Hist.), London.

A NEW EOCENE PRIMATE GENUS, CANTIUS 35

CLARK, W. E. LE GROS & THOMAS, D. P. 1952. The Miocene Lemuroids of East Africa.

Fossil Mammals of Africa, 5, 20 pp., 3 pis. British Museum (Nat. Hist.), London. COOPER, C. FORSTER. 1932. On some mammalian remains from the Lower Eocene of the

London Clay. Ann. Mag. Nat. Hist., London (10) 9 : 458-467, pis. 11-12. FILHOL, H. 1888. Description d'une nouvelle espece d'Adapis. Bull. Soc. philom. Paris,

7, 12 : 10-12. FORSYTH MAJOR, C. I. 1901. On some characters of the skull in the lemurs and monkeys

Proc. Zool. Soc. Land., 1901 : 129-153, pis. 11-13. GAZIN, C. L. 1958. A review of the Middle and Upper Eocene Primates of North America.

Smithson Misc. Coll., Washington, 126 : 1-112, pis. 1-14. GRANDIDIER, G. 1904. Un noveau Lemurien fossile de France, le Pronycticebus Gaudryi.

Bull. Mus. Hist. nat. Paris, 10 : 9-13, 3 figs.

1905. Les lemuriens disparus. Nouv. Arch. Mus. Hist. nat. Paris (4) 7 : 1-42.

GREGORY, W. K. 1920. On the structure and relations of Notharctus, an American Eocene

primate. Mem. Amer. Mus. Nat. Hist., New York (n.s.) 3 : 49-243, pis. 23-59.

1922. The origin and evolution of the human dentition, xviii + 548 pp., 14 pis. Baltimore.

GRANGER, W. & GREGORY, W. K. 1917. A revision of the Eocene Primates of the genus

Notharctus. Bull. Amer. Mus. Nat. Hist., New York, 37 : 841-859, pis. 103-107. HELLER, F. 1930. Die Saugetier fauna der mitteleozanen Braunkohle des Geiseltals bei

Halle. Jb. hallesch. Verb. Erf. mitteldtsch. Bodensch., Halle (n.f.) 9 : 13-41, pis. 1-5. — 1935. Amphilemur eocaenicus n. g. et n. sp., ein primitiver Primate aus dem Mitteleozan

des Geiseltales bei Halle a. S. Nova Acta Leop. Carol., Halle a. S. (n.s.) 2 : 293-300. HILL, W. C. O. 1953. Primates. Comparative Anatomy and Taxonomy. I. Strepsirhini.

xxiv + 798 pp., 34 pis. Edinburgh. 1955- Primates. Comparative Anatomy and Taxonomy. II. Haplorhini : Tarsioidea.

347 pp., 14 pis. Edinburgh. HURZELER, J. 1946. Gesneropithex Peyeri nov. gen. nov. spec, von Gosgen (Solothurn).

Eel. geol. Helv., Lausanne, 39, 2 : 354-361, 4 figs.

— 1947. Alsaticopithecus Leemanni nov. gen. nov. spec., ein neuer Primate aus dem unteren Lutetien von Buchsweiler im Unterelsass. Eel. geol. Helv., Lausanne, 40 : 343- 356, 12 figs.

— 1948. Zur Stammesgeschichte der Necrolemuriden. Abh. schweiz. palaont. Ges., Zurich, 66 : 1-46, 41 figs.

1950. liber die europaischen Apatemyiden. Eel. geol. Helv., Lausanne, 42, 2 : 485.

JEPSEN, G. L. 1934. A revision of the American Apatemyidae and the description of a new

genus, Sinclair ella, from the White River Oligocene of South Dakota. Proc. Amer. Phil.

Soc., Philadelphia, 74 : 287-305, pis. 1-3. LEMOINE, V. 1878. Communication sur les ossements fossiles des terrains tertiares inferieurs

des environs de Reims. Bull. Soc. Hist. nat. Reims, 1878 : 90-113, pis. 1-5. 1891. Etude d'ensemble sur les dents des mammiferes fossiles des environs de Reims.

Bull. Soc. geol. Fr., Paris (3) 19 : 263-290, pis. 10, n. LEMOINE, V. & AUMONIER, M. 1880. Terrains tertiaires des environs de Reims. Ass.

Franc. Avanc. Sci., Paris, 9 : 605-619, pi. 5. MATTHES, H. W. 1957- Die mitteleozane Saugerfauna des Geiseltales and ihre verwand-

schaftlichen Beziehungen. Wiss. Z. Univ. Halle, Math. Nat., 7 : 37-62, 22 figs. MCKENNA, M. C. 1960. Fossil mammalia from the early Wasatchian Four Mile fauna,

Eocene of northwest Colorado. Bull. Dep. Geol. Univ. Calif., Berkeley, 37 : 1-130,

64 figs. OSBORN, H. F. 1891. A review of the Cernaysian Mammalia. Proc. Acad. Nat. Sci. Philad.,

1890 : 51-62, 6 figs.

PIVETEAU, J. 1957. Primates, paleontologie humain. Traite de Paleont., Paris, 7 : 1-675. RUSSELL, D. E. 1960. Le crane de Plesiadapis. Bull. Soc. geol. Fr., Paris, 7 : 312-314,

pi. 18.

36 A NEW EOCENE PRIMATE GENUS, CANTIUS

RUTIMEYER, L. 1862. Eocane Saugethiere aus dem Gebiete des schweizerischen Jura.

Denkschr. schweiz. Ges. Naturw., Zurich, 19 : 1-248, pis. 1-6. — 1891. Die Eocane Saugethier-welt von Egerkingen. Abh. schweiz. palaont. Ges., Zurich,

18 : 1-153, pls- T~8- SIMONS, E. L. 1961. Notes on Eocene Tarsioids and a revision of some Necrolemurinae.

Bull. Brit. Mus. (Nat. Hist.) Geol., London, 5 : 43-69, pis. 12-14.

- 19610. The dentition of Ourayia : — its bearing on relationships of omomyid prosimians.

Postilla, Yale Peabody Mus., New Haven, Conn., 54 : 1-20, 3 figs. SIMONS, E. L. & RUSSELL, D. E. 1960. Notes on the cranial anatomy of Necrolemur. Breviora

Mus. Comp. Zool. Harv., Cambridge, Mass., 127 : 1-14, 3 figs. SIMPSON, G. G. 1940. Studies on the earliest primates. Bull. Amer. Mus. Nat. Hist., New

York, 77 : 185-212, 8 figs. 1945- The principles of classification and a classification of mammals. Bull. Amer. Mus.

Nat. Hist., New York, 85 : 1-350. - 1955. The Phenacolemuridae, new family of early primates. Bull. Amer. Mus. Nat.

Hist., New York, 105 : 415-441, pis. 30-35. STEHLIN, H. G. 1912. Die Saugetiere des schweizerischen Eocaens. Abh. schweiz. palaont.

Ges., Zurich, 38 : 1165-1298, figs, 244-288. 1916. Die Saugetiere des schweizerischen Eocaens. Abh. schweiz. palaont. Ges., Zurich,

41 : 1299-1552, pis. 21-22. STEHLIN, H. G. & SCHAUB, S. 1951. Die trigonodontie der simplicidentaten nager. Abh.

schweiz palaont. Ges., Zurich, 67 : 1-385, 620 figs. TEILHARD DE CHARDIN, P. 1921. Les mammiferes de 1'Eocene inferieur Fran9ais et leurs

gisements. Ann. Paleont., Paris, 10 : 171-176 ; 11 : 9-116, 42 figs. WEIGELT, J. 1933. Neue Primaten aus der mitteleozanen (oberluteitischen) Braunkohle des

Geiseltals. Nova Acta Leop. Carol., Halle (n.f.) 1 : 97-156, pis. i-u.

PLATE i Cantius eppsi (Cooper)

A. Right maxilla, B.M.N.H., M 15145, with P3-M2. B. Right mandible, B.M.N.H., M 13773 (Type), with P3-M3. x 6-0 approx.

Bull. B.M. (N.H.) Geol. 7, i

PLATE i

A

\

PLATE 2

Protoadapis klatti (Weigelt) Anterior dentition, G.P.I. H. 4258. xya approx.

Bull. B.M. (N.H.) Geol. 7, t

PLATE 2

PLATE 3

Protoadapis klatti (Weigelt)

Specimens of Protoadapis at Halle. A. Right M3, G.P.I.H. 7325 ; B. Right M1, G.P.I. H. 4292 ; c. Right M2, cf. Protoadapis, G.P.I.H. 4238 ; D. Left M3, G.P I H 4292 • E Left M2-3, Left P4_M8, G.P.I.H. 4310. All x 8 -o approx.

(Photographs slightly retouched.)

Bull. B.M. (N.H.) Geol. 7, i

PLATE 3

A

B

PRINTED IN GREAT BRITAIN BY ADLARD AND SON, LIMITED BARTHOLOMEW PRESS DORKING

THE BRACHIOPOD GENUS CYCLOTHYRIS

E. F. OWEN

BULLETIN OF THE BRITISH MUSEUM (NATURAL HISTORY)

GEOLOGY Vol. 7 No. 2

LONDON: 1962

THE BRACHIOPOD GENUS CYCLOTHYRIS

BY

ELLIS FREDERIC OWEN

Pp- 37-63 ; •?&• 4. 5 ; 10 Text-figures

BULLETIN OF THE BRITISH MUSEUM (NATURAL HISTORY)

GEOLOGY Vol. 7 No. z

LONDON: 1962

THE BULLETIN OF THE BRITISH MUSEUM (NATURAL HISTORY), instituted in 1949, is issued in Jive series, corresponding to the Departments of the Museum, and an Historical series.

Parts will appear at irregular intervals as they become ready. Volumes will contain about three or four hundred pages, and will not necessarily be completed within one calendar year.

This paper is Vol. 7 No. 2 of the Geological (Palaeontologicai) series.

Trustees of the British Museum, 1962

PRINTED BY ORDER OF THE TRUSTEES OF THE BRITISH MUSEUM

Issued May, 1962 Price Fourteen Shillings

THE BRACHIOPOD GENUS CYCLOTHYRIS

By ELLIS FREDERIC OWEN

SYNOPSIS

A revision of M'Coy's genus Cyclothyris from the Upper Aptian is made and serial sections of the type-species presented for the first time. In addition eight other species of Cyclothyris are described, two of these are new species. The subfamily Cyclothyrinae of Makridin is emended and discussed. A comparison is made between Cyclothyris from the Lower Greensand and the Upper Chalk genus Cretirhynchia. A new generic name is proposed for five Lower Cretaceous Rhynchonellidae.

INTRODUCTION

THE name Cyclothyris was first used by M'Coy (1844 : 103) to indicate a group of brachiopods which he called "... those curious species in which the deltidium completely surrounds the foramen ". No geological age was mentioned nor was any species named. M'Coy did, however, figure a specimen (p. 150, fig. 29) which is probably lost.

From the beak characters of Mesozoic and Palaeozoic Rhynchonellidae it seems likely that M'Coy was referring to an early Cretaceous genus and, from the arrange- ment of the costae, shell outline, growth-marks and interarea as seen in his fig. 29, it is probable that M'Coy had selected a specimen of Aptian age.

FIG. i. Copy of M'Coy's (1844) original illustration of fig. 29, p. 150.

Previously, J. de C. Sowerby (1825 : 165, pi. 502, fig. i) had described and figured a rhynchonellid from the Upper Aptian, Sponge Gravel of Faringdon, Berkshire under the name Terebratula lata. He subsequently changed this specific name to T. latissima in the index to the Mineral Conchology published in 1829, having realized that his father J. Sowerby (1815 : 227) had already used the name T. lata for a brachiopod from the Drift of Lowestoft, Suffolk.

The outline, arrangement of costae and growth-lines of J. de C. Sowerby's figured specimen of Terebratula latissima (pi. 502, fig. i) agree with the figure of M'Coy's genus Cyclothyris. This similarity was certainly noted by Davidson (1855 : 93) who included Cyclothyris in his synonymy of Fischer's genus Rhynchonella and quoted C. latissima in brackets after the generic name, probably as a typical species of Cyclothyris.

GEOL. 7, 2. 2

4o

THE BRACHIOPOD GENUS CYCLOTHYRIS

Buckman (1906 : 326) was the first to designate T. latissima J. de C. Sowerby as the type species of Cyclothyris and subsequent authors have followed Buckman. The genus was not further investigated nor adequately defined until Hertlein & Grant (1944 : 61) published a full synonymy in their work on Caenozoic Brachiopoda from western North America.

Stratigraphically the genus ranges from the Upper Aptian to the Upper Cenomanian and was probably developed from such a middle European form as Lepidorhynchia which Burn (1956 : 689) described from the Neocomian, Lower Barremian, of

Dm

B

SP

FIG. 2. Four drawings illustrating some of the internal characters of Cyclothyris. A. Pedicle valve showing subquadrate hinge-teeth (Ht) and large pear-shaped diductor muscle-scars (Dm). B. Subparallel dental lameleae in pedicle valve (Dl). c. Brachial valve showing ventral surface of the crura (Cr). D. Brachial valve showing the dorsal concave surface of the crura (Cr) and deep crenulated dental sockets (Ts) and short septum (Sp).

Switzerland. Cyclothyris appears to have been confined chiefly to the European continent, although a notable exception to this is C. americana described and figured by Cooper (1955 : 3, pi. i) from the Aptian of Arizona. Examples of this species have not yet been examined by the writer but to judge from the figure on Cooper's pi. i it may well belong to this genus. Other species referred to Cyclothyris by Hertlein & Grant (1944 : 63) are probably not referable to the genus, but careful examination including the use of serial sections is necessary before any conclusions can be drawn. Another species from the American continent referred to this genus is Cyclothyris ? subtrigonalis Imlay from the Lower Neocomian of Mexico. This is shown in serial section (Imlay, 1937 : 571) to have a persistent septum in the brachial

THE BRACHIOPOD GENUS CYCLOTHYRIS 41

valve and a large septalium, both characters which do not appear in serial sections of the type species C. latissima (J. de C. Sowerby).

In the English Aptian the genus is represented by at least four species namely, C. latissima, C. depressa (J. de C. Sowerby), C. antidichotoma (Buvignier) and C. lepida sp. n., but there may be others not yet investigated. The rhynchonelloid species " R." nuciformis described from the Upper Aptian of Faringdon by J. de C. Sowerby (1825 : 166), and often erroneously referred to Cydothyris, is probably related to a species described by the writer (Owen, 1960 : 253) as Lamellaerhynchia larwoodi from the Upper Aptian of Upware, Cambridge.

B

D

FIG. 3. Diagram illustrating different types of anterior commissure found in Cydothyris. A. Broadly arcuate. B. Trapezoidal, c. Asymmetrical. D. High arcuate.

Some of these Upper Aptian species are recognizable as passage forms in the Lower Albian deposits at Leighton Buzzard, Bedfordshire. Middlemiss (1959 : 138) regards the Shenley Limestone fauna as essentially of an Albian-Cenomanian type. While possibly true of the terebratuloid fauna it is certainly not of the rhynchonelloids. With the possible exception of two species the fauna is distinctly Albian, having close affinities with Upper Aptian faunas at Brickhill and Upware in this country and Lower Albian faunas at Grandpre, Haute-Savoie and Haute-Saone, France.

Two Lower Albian species of Cydothyris are described here from the Leymeriella tardefurcata Zone of the Shenley Limestone of Leighton Buzzard, Bedfordshire. One is the widely quoted C. antidichotoma (Buvignier), which also occurs in the Upper Aptian, and C. levis sp. n.

By far the commonest Cenomanian species of Cydothyris is C. difformis (Valen- ciennes in Lamarck) which ranges from the Lower to Middle Cenomanian. It has

42 THE BRACHIOPOD GENUS CYCLOTHYRIS

been recorded from Wiltshire, Devon and Dorset in England and from Normandy in France, Tournai in Belgium, and Essen in North Germany. Examples of this species with its many varieties are to be found in the general collections of the British Museum (Natural History).

Apart from C. difformis, other Cenomanian species here described include C. scaldi- sensis (d'Archiac) from the Tourtia of Belgium, and C. schloenbachi (Davidson), a common fossil in the Lower Cenomanian of Somerset and Devon.

The generic name Burrirhynchia is proposed for " Rhynchonella " leightonensis Walker from the Lower Albian, L. tardefurcata Zone of Shenley Hill, Leighton Buzzard, Bedfordshire. This genus is also represented in the Upper Aptian, P. nut- fieldensis Zone, of Upware, Cambridge and Brickhill, Buckinghamshire by the species " R." cantabrigensis Davidson.

An emended description of " R." leightonensis together with serial sections were published by the writer (Owen, 1956 : 166, 167) and these may be compared with serial sections of Burrirhynchia cantabrigensis (Davidson) figured here as Text-fig. 10.

TERMINOLOGY

The terms used in the systematic descriptions here are according to Thomson (1927), Muir-Wood (1934) and Muir-Wood & Cooper (1960).

Cyclothyrid. As applied to the deltidial plates was proposed by the writer (Owen, 1956 : 165) to replace the term " auriculate " which was used by Buckman (1918 : 18) to describe the encirclement of the foramen by the deltidial plates.

Sulcus. The term sinus has often been used by authors to describe the median sulcation of a valve. Muir-Wood & Cooper (1960 : 8) pointed out that the term for this condition should be sulcus. Their definition was in connection with productoids, but the term is equally applicable to the rhynchonelloids and is quoted as " Sulcus. — A major depression in either valve usually median in position, which helps channel the outgoing stream in feeding. A median fold is usually opposite a median sulcus in the productoids."

The term sulcus, therefore, as defined by Muir-Wood & Cooper is used throughout the following systematic descriptions.

In the same publication Muir-Wood & Cooper (1960 : 14) redefined the following terms :

Capillae. Fine radial, elevated lines (with more than 25 in 10 mm.).

Costellae. Radial lines coarser than capillae (about 15-25 in 10 mm.).

In the following systematic descriptions the measurement of 10 mm. is taken to indicate a position 10 mm. wide at a distance 10 mm. anterior to the umbo on the brachial valve. These terms have been used as above in the descriptions of C. anti- dichotoma, C. lepida sp. n. and C. levis sp. n.

Dimensions of Cyclothyris specimens are given in millimetres but are defined generally as :

Small, measuring up to 15 mm. long, 20 mm. wide.

Medium, 16-28 mm. long, 21-38 mm. wide.

Large, 29-35 mm. long, 39-45 mm. wide.

THE BRACHIOPOD GENUS CYCLOTHYRIS 43

SYSTEMATIC DESCRIPTIONS

Superfamily RHYNCHONELLACEA Schuchert, 1896 Family RHYNCHONELLIDAE Gray, 1848

Rzhonitskaya (1959), in an attempt to reclassify the rhynchonelloids, cited the subfamily Cyclothyrinae which was proposed by Makridin (1955) for certain rhyn- chonelloid genera ranging from the Trias to the Cretaceous. Makridin's definition quoted by Rzhonitskaya is translated by Mrs. G. A. Cooper, Washington, U.S.A. as : " Ribbed or plicate rhynchonellids without a septalium ; septa may be developed or be absent, hinge-plate divided."

This very broad definition included such genera as Stolmorhynchia Buckman, 1914 and Lacunosella Wisniewska, 1932 which, unlike most of the other genera included, are known to possess falcifer crura and are quite distinct from those genera bearing radulifer crura.

The following emended definition of Makridin's subfamily Cyclothyrinae is there- fore proposed :

Costate, costellate, capillate or plicate rhynchonelloids without a septalium ; sep- tum developed or absent, hinge-plates divided, crura radulifer, foramen hypothyrid. This would include the following genera : Cyclothyris M'Coy, 1844. Cretirhynchia Pettitt, 1950. Sulcirhynchia Burri, 1953. Lamellaerhynchia Burri, 1953. Plicarostrum Burri, 1953. Lepidorhynchia Burri, 1956. Burrirhynchia nov. RANGE. Cretaceous.

Subfamily CYCLOTHYRINAE Makridin, 1955 emended Genus CYCLOTHYRIS M'Coy, 1844

1844 Cyclothyris M'Coy, p. 103, 150, fig. 29.

1852 Cyclothyris Davidson, p. 93.

1877 Cyclothyris Dall, p. 24.

1906 Cyclothyris Buckman, p. 18.

1913 Cyclothyris Schuchert in Zittel, p. 398.

1918 Cyclothyris Buckman, pi. 14, fig. ia.

TYPE-SPECIES (by subsequent designation, Buckman, 1906). Terebmtula latissima J. de C. Sowerby.

EMENDED DIAGNOSIS. Medium to large biconvex rhynchonellidae, oval to subtri- angular in outline. Shell multicostate, costae sharp, coarse to fine, subangular to rounded. Growth-lines lamellar to step-like. Anterior commissure uniplicate. Beak-ridges usually distinct, interarea well defined. Foramen medium to large, circular. Deltidial plates conjunct, cyclothyrid.

44 THE BRACHIOPOD GENUS CYCLOTHYRIS

Internal characters. Umbonal cavities oval in cross-section. Denticulae well developed. Teeth large, deeply inserted. Dental lamellae strong, subparallel. Hinge-plates broad, slightly arched in transverse section, divided terminally. Crura anteriorly concave.

DESCRIPTION. Cyclothyris comprises a very variable group of medium to large rhynchonellidae. With the exception of perhaps one or two species, the outline is distinctly transversely oval. A fold and sulcus develop late and there is usually considerable lateral and anterior thickening of the margins in the gerontic stage. The ornament consists chiefly of strong costae with marked growth-lines sometimes becoming lamellar. The type and position on the valves of the growth-lines is regarded as a specific character and can be linked with type of costation when group- ing the species. The members of the latissima group, for instance, have numerous subangular or rounded radiating costae with fairly distinct growth-lines at about one-third the distance from the umbo, and approximately three to five at about two-thirds the distance from the umbo. They tend to be closer together or more lamellar and less prominent at the anterior margin. Bifurcation of the costae in adult forms is rare.

In some species, notably C. antidichotoma (Buvignier), the ornament shows con- siderable deviation from the typical. Davidson (1851, pi. 14) in the species Capil- lirhynchia urighti (Davidson) from the Inferior Oolite, and Ager (1958 : 69) in Furcirhynchia furcata Buckman from the Lias illustrated a similar kind of ornament. In the genus Cyclothyris this type of ornament is regarded as a specific character.

Marked uniplication of the anterior margin is a strong feature but some species show a tendency to produce an asymmetrical commissure. These aberrant forms are noticeable throughout the generic range and particularly in the Cenomanian species C. difformis.

Some species, for instance C. scaldisensis (d'Archiac), are characterized by their large circular foramen. This is a common feature of the latissima group.

Internal characters

Pedicle valve. The umbonal cavity is roughly oval in cross-section, a pedicle collar being developed within the first 4 mm. The cyclothyrid deltidium is seen in transverse section as two outwardly curving plates, one on either side of the foramen. The crenulated hinge-teeth are thick, quadrate and deeply inserted, expanding dorsally. The diductor muscle-scars are large and triangular. The adductor muscle- scars are too faint for adequate description.

Brachial valve. No cardinal process is developed. The hinge-plates are slender and gently arched ventrally. Inner and outer socket-ridges are well defined. The median septum is short and does not support the hinge-plates. Radulifer crura originate from the distal parts of the hinge-plates and curve ventrally. Each terminates in a Y-shaped fork which may be slightly deflected dorsally or remains almost horizontal to the sides of the valve.

DISCUSSION. The chief distinguishing characters of Cyclothyris, apart from its general outline, are the extensive interarea, absence of bifurcation and intercalation

THE BRACHIOPOD GENUS CYCLOTHYRIS 45

of costae in adult forms, large circular foramen and incipient fold in the brachial valve. The arched and divided or forked hinge-plates, as seen in transverse section, distinguish it from other Cretaceous rhynchonellid genera. It is readily distinguished from Orbirhynchia (Pettitt, 1954) in possessing radulifer crura.

The stratigraphical zones quoted for species of Cyclothyris from the Lower Green- sand are according to Casey (1961).

Cyclothyris latissima (]. de C. Sowerby) (PI. 4, figs. 7, 8 ; Text-fig. 4)

1825 Terebratula lata J. de C. Sowerby (non T. lata J. Sowerby), p. 165, pi. 502, fig. i.

1829 Terebratula latissima J. de C. Sowerby, Index.

1852 Rhynchonella latissima (J. de C. Sowerby) : Davidson, p. 82, pi. n, figs. 15—22.

1918 Cyclothyris latissima (J. de C. Sowerby) : Buckman, p. 14, pi. 14, fig. ia.

1950 Cyclothyris latissima (J. de C. Sowerby) : Pettitt, pi. i, figs. 14, 15.

1956 Cyclothyris latissima (J. de C. Sowerby) : Owen, pi. 3, fig. 6.

EMENDED DIAGNOSIS. Medium sized Cyclothyris approximately 21 mm. long, 24 mm. wide and 13 mm. thick. Transversely oval to subtriangular in outline, lenticular in anterior contour. Brachial valve convex, with broad, flat almost imperceptible median fold. Pedicle valve less convex, with broad shallow sulcus. Anterior commissure broadly arcuate. Umbo short, thick, slightly incurved. Fora- men large. Deltidial plates well exposed. Each valve ornamented by about 60 rounded or subangular costellae (23 per 10 mm.) with approximately 13 on the fold and a corresponding number in the sulcus.

LECTOTYPE. In the original description of the species J. de C. Sowerby (1825 : 165) quotes three localities, Faringdon, Sidmouth, and Devizes Canal. The species is represented in the Sowerby Collection, British Museum (Natural History) by three specimens from the above localities. Of these, the specimen from Faringdon was selected and figured as lectotype of the species by Pettitt (1950, pi. i). It is registered in the British Museum (Natural History) collections as 6.61499. Of the two remain- ing syntypes, one is recognizable as a young C. difformis (Valenciennes in Lamarck) from the Cenomanian of Sidmouth, Devon, while the other is crushed and too badly damaged for identification.

DESCRIPTION. Although C. latissima does not seem to show the same range of variation as other species of Cyclothyris, a marked variant occurs at Faringdon, Berkshire and at Brickhill, Buckinghamshire and reaches dimensions considerably larger than the typical form, measuring approximately 25 mm. long, 34 mm. wide and 18 mm. thick. The dimensions of the lectotype are 21 mm. long, 28 mm. wide and 12 mm. thick. A fine series of specimens illustrating the above variant are to be found in the collections of the Sedgwick Museum, Cambridge numbered SM. 6.25682-6.25708.

The outline of the shell of C. latissima remains oval to subtriangular with a broad flat fold on the brachial valve. The ornament consists of approximately 60 costellae on each valve, which are characteristically subangular or rounded and interrupted by step-like or fairly steep concentric growth-lines at about one-third the distance

GEOL. 7, 2. 2§

46

THE BRACHIOPOD GENUS CYCLOTHYR1S

from the umbo and again at about two-thirds the distance from the umbo. Growth- lines at the anterior margin tend to be more numerous, usually about 3 to 5 and are lamellar.

Internal structure. As for genus. Text-fig. 4.

Cyclothyris latissima can be distinguished from other Aptian species of Cydothyris by its more acutely triangular outline, more extensive interarea, less marked anterior fold and more prominent growth-lines. It differs from C. depressa (J. de C. Sowerby)

FIG. 4. A series of fifteen transverse serial sections through the umbonal part of a specimen of Cyclothyris latissima (J. de C. Sowerby) from the type locality, Faringdon, Berkshire. BM. 66.5482. X2.

in its less produced beak, larger dimensions, less angular costellae and more arcuate anterior commissure. It is less convex than other Cyclothyris species with the excep- tion of C. scaldisensis (d'Archiac) from the Tourtia of Belgium which it resembles, but can be distinguished from this species by its smaller dimensions, more prominent growth-lines and less well-developed interarea and beak-ridges.

DISTRIBUTION. Apart from the type locality at Faringdon, Berkshire, where it occurs in the Tropaeum subarcticum subzone of the Parahoplites nutfieldensis Zone, C. latissima has also been found in the P. nutfieldensis Zone at Upware, Cambridge and from the junction of the Hythe and Sandgate Beds on the foreshore just west of Folkestone Harbour, Kent.

THE BRACHIOPOD GENUS CYCLOTHYRIS 47

Cyclothyris antidichotoma (Buvignier) (PI. 4, figs. 3^6 ; Text-figs. 5, 6)

1842 Terebratula antidichotoma Buvignier, p. 533, pi. 4 fig. 8.

1847 Rhynchonella antidichotoma (Buvignier) d'Orbigny, p. 31, pi. 500, figs. 1-5.

1847 Rhynchonella antidichotoma (Buvignier) : Pictet & Roux, p. 534, pi. 50, figs. $a-g.

1872 Rhynchonella antidichotoma (Buvignier) : Pictet, p. 41, pi. 199, figs. 13-176.

1874 Terebratula antidichotoma Buvignier : Davidson, p. 65, pi. 8, figs. 19-21.

1903 Rhynchonella lineolata var. mirabilis Walker, p. 261, pi. 18, figs. ja-c.

EMENDED DIAGNOSIS. Medium to large biconvex Cyclothyris approximately

31 mm. long, 36 mm. wide and 15 mm. thick. Transversely oval to subcircular in outline. Brachial valve with broad, faintly developed median fold. Pedicle valve with wide, shallow sulcus, anteriorly developed. Anterior commissure broadly arcuate to trapezoidal. Umbo massive to sharp, slightly produced. Foramen large. Deltidial plates well exposed. Beak-ridges distinct, interarea extensive. Each valve ornamented with between 15 and 30 fine rounded costellae posteriorly and a few strong angular costae anteriorly.

TYPE SPECIMEN. The original specimen figured by Buvignier (1842, pi. 4, fig. 8) cannot be traced and is presumed lost. It is not proposed to erect a neotype of this species until more material from the type locality has been examined. The only available specimen said to be from the area of the type locality examined by the writer is in the d'Orbigny Collection, Museum Nationale d'Histoire Naturelle, Paris and is registered in the d'Orbigny catalogue as 6014. This specimen, stated to be from the Albian of Saulce, Ardennes, does not resemble Buvignier's figured specimen in general outline although the ornament is similar. Instead it resembles one of the more robust forms commonly found in England at Brickhill and Upware and regarded as an extreme variant. D'Orbigny (1847, pi. 500) figured two specimens both of which resemble the one figured by Buvignier (1842, pi. 4, fig. 8). Neither of these specimens is in the d'Orbigny Collection and their whereabouts cannot be ascer- tained.

DESCRIPTION. Buvignier's figure shows a large Cyclothyris measuring approximately

32 mm. long and 42 mm. wide, with a sharp beak, large foramen and ornament of fine costellae and strong costae which are the main distinguishing features. Specimens possessing similar features have been examined by the writer from Upware, Cam- bridgeshire, Brickhill, Buckinghamshire and Potton and Leighton Buzzard, Bed- fordshire. In addition collections of specimens also bearing these features from Albian localities in France and Switzerland have been studied in the Museum d'Histoire Naturelle, Geneva.

It is probable that the original specimen described by Buvignier came from the Gault of Grandpre, although specimens of other species from this locality are usually preserved as internal casts in phosphatized sandy clay. Buvignier's specimen, however, has a well-preserved shell and may have come from the beds below the phosphate workings which are known to be of Upper Aptian age.

In England, the Upper Aptian forms occurring at Brickhill and Upware differ from Buvignier's figured specimen in their more circular general outline and more

48

THE BRACHIOPOD GENUS CYCLOTHYRIS

convex valves, although variants approaching the typical form have been found. The Lower Albian forms from Leighton Buzzard, while agreeing in general outline and proportions with Buvignier's figure, have a less acute apical angle, less produced beak and smaller interarea and are much nearer a form which occurs at Goudiniere, Grand St. Bernard and at Mont Saxonet, Savoie, France. This form is represented

o .0

0-2

FIG. 5. Eighteen transverse serial sections through the umbonal part of Cyclothyris antidichotoma (Buvignier) from the Upper Aptian, Upware, Cambridge. BM. 6.25753. X 2.

in the Davidson Collection, British Museum (Natural History) by three specimens from Goudiniere registered as 66.41485-87. Another specimen showing a marked resemblance to the Leighton Buzzard form comes from the Albian of Vergys, Upper Savoie and is registered as BM. 6.35284.

Young forms of this species were thought to belong to a new variety by Walker (1903 : 261) who described them as Rhynchonella lineolata var. mirabilis. They are

THE BRACHIOPOD GENUS CYCLOTHYRIS

49

usually more triangular in outline than the adult forms, with marked anterior sulca- tion of both valves. The large marginal costae are less numerous at this stage and the median fold in the brachial valve is not developed. Examples of this juvenile stage were figured by Pictet & Roux (1847, pi. 50) and by Pictet (1872, pi. 919) as R. anti- dichotoma (Buvignier) .

The ornament of fine costellae and coarse costae running into one another is characteristic of the species but, as already stated, authors have described a similar

0-2

FIG. 6. Fourteen transverse serial sections through the umbonal part of Cyclothyris antidichotoma (Buvignier) from the Lower Albian, Shenley Hill, Leighton Buzzard, Bedfordshire. BM. 66.17561. x 2.

feature on species in the Jurassic, and less notably, on Upper Cretaceous species such as Cretirhynchia octoplicata (J. Sowerby) as figured by Davidson (1852, pi. 10, figs, i-n).

Although there may be sufficient grounds both morphologically and stratigraphic- ally for separating the Upper Aptian forms from those in the Lower Albian of this country, the writer proposes to leave this extremely well-known species as it is at present interpreted until more material from Grandpre, or at least from the French Ardennes, is available and the limits of variation are possible to define.

DISTRIBUTION. C. antidichotoma as at present interpreted is a common fossil in

50 THE BRACHIOPOD GENUS CYCLOTHYRIS

the Upper Aptian, P. nutfieldensis Zone, at Upware, Cambridge and Brickhill, Buckinghamshire and occurs, though not commonly, in the Lower Albian, Leymeriella tardefurcata Zone at Leighton Buzzard, Bedfordshire. It has also been collected from the Albian of Mont Saxonet and Goudiniere and from the Ardennes, France.

Cyclothyris depressa (J. de C. Sowerby) (PI. 4, fig- ii)

1825 Terebratula depressa J. de C. Sowerby, p. 165, pi. 502, fig. 3.

1852 Rhynchonella depressa (J. de C. Sowerby) Davidson, p. 89, pi. n, figs. 28-32.

EMENDED DIAGNOSIS. Small Cyclothyris about 9 mm. long, n mm. wide and 8 mm. thick. Elongate-triangular in outline. Brachial valve convex with moderately well-developed median fold. Pedicle valve less convex with shallow sulcus. Anterior commissure uniplicate with trapezoidal linguiform extension. Beak suberect, apical angle acute. Foramen large. Deltidial plates well exposed. Shell ornamented by about 25-28 sharp, angular, radiating costae originating from the umbones, with 6 on fold and 7-8 in sulcus.

LECTOTYPE. In the original description of the species J. de C. Sowerby (1825) figured two specimens as fig. 3 on his pi. 502. Of these the larger of the two specimens is shown in dorsal and ventral views. This specimen is here selected as lectotype of the species. It is in the Sowerby Collection, British Museum (Natural History) No. 6.61468, together with the second figured specimen (6.61469) and three other syntypes (6.61470-72) which are also referable to C. depressa.

DESCRIPTION. Apart from its small dimensions, the distinctive characters of this species are those of the beak, which is slightly produced, sharp and suberect. The large circular foramen shows the cyclothyrid deltidial plates to advantage. The pedicle valve has a marked trapezoidal linguiform extension. The sharp, angular costae show no signs of bifurcation or intercalation. They are interrupted only by a faint growth-line which appears at about two-thirds the distance from the umbo to anterior margin.

Internal structure. As for genus.

REMARKS. C. depressa has been grouped with C. schloenbachi (Davidson) since the two species have much in common. Their general outline and profile is roughly the same with a well-defined fold and sulcus. The linguiform extension is trapezoidal in shape. Both species are relatively small and seem to show the same extremes of variation with fine and coarse costation. C. depressa, however, is distinguished from C. schloenbachi by its more acutely triangular outline, slightly produced beak and shallower sulcus in the pedicle valve and well-developed fold on the brachial valve. It differs from C. latissima in its general triangular outline, angular costation, pro- duced beak, smaller dimensions and trapezoidal linguiform extension.

DISTRIBUTION. C. depressa is commonly found in association with C. latissima in the Upper Aptian (P. nutfieldensis Zone) of Faringdon, Berkshire and also at the same horizon at Brickhill, Buckinghamshire.

THE BRACHIOPOD GENUS CYCLOTHYRIS 51

Cyclothyris difformis (Valenciennes in Lamarck) (PI. 5, figs. 1-7 ; Text-figs. 7, 8)

1819 Terebratula difformis Valenciennes in Lamarck, p. 255, fig. indicated Encycl. Meth., 1789, pi. 242, fig. 5.

Terebratula dimidiata J. Sowerby, p. 138, pi. 277, fig. 5.

Terebratula gallina Brongniart, p. 84, pi. 9, fig. 2.

Terebratula deformis Lamarck : Defrance, p. 160, pi. 5, fig. 3.

Rhynchonella compressa (Lamarck) : d'Orbigny, p. 35, pi. 497, figs. 1-5.

Terebratula difformis Lamarck : Davidson, p. 433, pi. 15, fig. 48.

Terebratula compressa Lamarck : Davidson, p. 80, pi. n, figs. 4, 5.

Terebratula difformis Lamarck : Quenstedt, p. 696, pi. 54, fig. 2. 1900 Rhynchonella difformis (Lamarck) Jukes-Browne, p. 65, figs. 41, 42. 1918 Terebratula difformis Valenciennes in Lamarck : Clerc & Favre, pi. 15, fig. 84.

EMENDED DIAGNOSIS. Medium-sized Cyclothyris approximately 23 mm. long, 31 mm. wide and 17 mm. thick. Shell biconvex, fold low, indistinct, oval to sub- triangular in outline. Anterior commissure with well-marked uniplication. Umbo short, massive, slightly incurved. Foramen fairly large. Deltidial plates conjunct, well exposed. Beak-ridges distinct. Interarea extensive. About 40-45 costae on either valve (14 per 10 mm.) with 9 on fold and 10-11 in sulcus.

LECTOTYPE. Owing to Lamarck's blindness the brachiopods in his " Animaux sans Vertebres " (vol. 6, 1819) were described by his pupil A. Valenciennes from specimens in Lamarck's own collection. In the description of Terebratula difformis (p. 255) Valenciennes indicated a specimen illustrated in Encyclopedic Methodique (1789, pi. 242, fig. 5) quoting the localities " near Le Mans, and also at Cap la Heve, near Le Havre " both Cenomanian localities. No type specimen was named or indicated and the whereabouts of the figured specimen is not known.

Davidson (1850 : 433) in a description of Lamarck's species states that he bor- rowed the ten specimens used by Valenciennes in his original description and figured one of them as T. difformis (pi. 15, fig. 48). This would have served as lectotype of the species had the specimen not been subsequently lost or mislaid. A further specimen figured by Clerc & Favre (1918, pi. 15, figs. 8^a-d) has therefore been selected as lectotype of the species. This specimen is one of eight to be found under the name Terebratula difformis in the Lamarck Collection at the Museum d'Histoire Naturelle, Geneva and is registered as No. 48 in the Lamarck catalogue. From the mode of preservation and adhering matrix it was almost certainly collected from the Lower Cenomanian of the Normandy coast. The other seven specimens are probably of Jurassic age. The dimensions of the lectotype are : 23 mm. long, 31 mm. wide and 17 mm. thick.

DESCRIPTION. C. difformis is an extremely variable species ranging in outline from subcircular to transversely oval to subtriangular. The ornament usually consists of about 45 coarse to relatively fine costae originating from the umbo of each valve and becoming more elevated towards the anterolateral margins. These costae are usually interrupted by one or two step-like growth-lines situated at about one-half to two- thirds the distance from the umbo to the anterior margin.

The umbo varies from short to massive to slightly produced. An extensive interarea

52 THE BRACHIOPOD GENUS CYCLOTHYRIS

with distinct beak-ridges is seen throughout the range of variation. The median fold on the brachial valve remains indistinct while the broad, shallow sulcus in the pedicle valve is late in development. The linguiform extension varies from broadly arcuate to trapezoidal but asymmetry of the anterior commissure is a notable character.

Variants worthy of special note occur at Wilmington, south Devon and at Cap la Heve, Normandy. One of the Wilmington varieties departs from the typical in having more convex valves, shorter umbo, smaller foramen and more acutely arched

FIG. 7. Diagram illustrating thirteen variants of Cyclothyris difformis (Valenciennes in Lamarck) from Wiltshire, south Devonshire, and Normandy.

anterior commissure. The variety usually found on the Normandy coast, on the other hand, has a slightly produced beak, less convex valves and commonly exhibits an asymmetrical anterior commissure.

Another notable variant occurs in the Lower Cenomanian, Tourtia, Belgium. Six well-preserved specimens in the British Museum (Natural History) are numbered 66.41475-80. The same variety occurs in the Lower Cenomanian deposits of Essen, North Germany and is represented in the same museum by a single specimen (BB.

4I473)-

The specimen figured and described as Terebratula dimidiata by J. Sowerby (1821 : 138, pi. 277, fig. 5) from Halldown near Chudleigh, south-east Devon, is a large, almost sphaeroidal rhynchonellid with coarse costae, sharp, produced beak and

THE BRACHIOPOD GENUS CYCLOTHYRIS 53

asymmetrical anterior commissure. This is either an extreme variant of C. difformis or a pathological form.

A form somewhat resembling the outline of Sowerby's T. dimidiata but with finer costae, is figured by d'Orbigny (1847, pi- 49$, figs. 6-9) from the Charentes as Rhynchonella difformis. Some authors have followed d'Orbigny 's interpretation of Lamarck's species and Mile G. Fage (1935 : 433, pi. n), in a description of some Upper Cretaceous rhynchonellids from the Charentes, illustrated an evolutionary development from R. difformis d'Orbigny to a variety R. globata Fage. Her figured specimen of R. difformis is stated to have been collected from the Coniacian.

A specimen figured by J. de C. Sowerby (1836, pi. 18, fig. 2) as T. dilatata was stated in the explanation of the plates to have been collected from Blackdown, south Dorset.

FIG. 8. A series of twelve transverse serial sections through the umbonal part of Cyclo- thyris difformis (Valenciennes in Lamarck) from the lower Cenomanian, Cap la Heve, near Le Havre, Normandy. BM. 6.35224. x 2.

This figure shows a remarkable similarity to a specimen figured by Schloenbach (1867, pi. 23, fig. 2) as C. difformis from the Lower Cenomanian of Essen, Germany.

DISTRIBUTION. C. difformis ranges from the Lower to Middle Cenomanian of the west of England, Normandy and North Germany. In the type area of the Normandy coast it occurs in the remanie bed at the base of the Cenomanian, is abundant in the Lower Cenomanian and is less common, but still well represented in the Middle Cenomanian.

In England the species is almost unrepresented in the Middle Cenomanian though rare examples have been found in the Middle Cenomanian basement beds of west Dorset. It is abundant, however, in the Lower Cenomanian, occurring in Wiltshire (Warminster Greensand) and the Devon coast, as well as in the Isle of Wight. A well-marked variant is the commonest brachiopod in the sandy Lower Cenomanian

54 THE BRACHIOPOD GENUS CYCLOTHYRIS

of Wilmington, south Devon. It is said to occur in the dispar Zone at Punfield Cove, south Dorset but specimens of this species are more likely to have been collected from the bottom Cenomanian beds. Its occurrence below this level is uncertain.

Cyclothyris compressa (Valenciennes in Lamarck) (PL 5, ng. 8)

1819 Terebratula compressa Valenciennes in Lamarck, p. 256, No. 54.

1850 Terebratula compressa Lamarck : Davidson, p. 455, pi. 15, fig. 54.

1918 Terebratula compressa Valenciennes in Lamarck : Clerc & Favre, pi. 19, figs. 117, 119.

EMENDED DIAGNOSIS. Cyclothyris, about 28 mm. long, 32 mm. wide and 14 mm. thick. Distinctly subtriangular in general outline ; brachial valve convex with faint median fold. Pedicle valve posteriorly convex with broad, shallow median sulcus. Both valves ornamented by about 40 strong, acutely angular, radiating costae, (8 per 10 mm.) with 8 on fold and a corresponding number in sulcus. Concentric growth-lines very faint. Beak short, slender, slightly incurved. Beak-ridges distinct, interarea small. Deltidial plates triangular, foramen small.

LECTOTYPE. The specimen here selected as lectotype of the species is one of four syntypes in the Lamarck Collection at the Museum d'Histoire Naturelle, Geneva and is numbered in the Lamarck Catalogue as No. 54. The specimen was figured by Davidson (1850, pi. 15, fig. 54) and by Clerc & Favre (1918, pi. 19, fig. 117). It was collected from the Upper Cenomanian of Coulaines near Le Mans in the Sarthe, south-west of the Paris basin. The dimensions of the lectotype are : 29 mm. long, 35 mm. wide and 14 mm. thick.

DESCRIPTION. C. compressa is one of the most distinctive species of Cyclothyris. It is characterized by its acutely subtriangular outline and strong angular costae. It can be distinguished by its low, faintly developed median fold, trapezoidal lingui- form extension, and marginal thickening of the valves. It is probable that this species is a direct development of C. difformis. A specimen from the Tourtia of Belgium, showing characters of both species is in the British Museum (Natural History) numbered BM. 6.1889. Another specimen figured by Davidson (1852, pi. n, figs. 4, 5) as C. compressa and figured here on PL 5, fig. 8 as C. difformis shows the general outline of C. difformis with the anterior and lateral contours and sharp angular costae of C. compressa but without the marginal thickening of the valves.

DISTRIBUTION. The species, originally described from Coulaines near Le Mans in the Sarthe, France is confined to the sandy Cenomanian of the south-west Paris basin. The typical form is characteristic of the Upper Cenomanian, Sables du Perche, where it is the only rhynchonellid present. Related but not identical forms occur in the beds above (Marnes a Ostrea biauriculata) and below (Sables et Gres du Mans).

Varieties, stated to belong to this species, were described by Cayeux (1949) from Le Havre but were not accompanied by any adequate description or illustration, nor were any type-specimens indicated.

THE BRACHIOPOD GENUS CYCLOTHYRIS 55

Cyclothyris schloenbachi (Davidson) (PI. 4, figs. 12, 13)

1852 Rhynchonella depressa vars. A and B, Davidson, p. 92, pi. 12, figs. 28-30. 1874 Rhynchonella schloenbachi Davidson, p. 59.

EMENDED DIAGNOSIS. Small Cyclothyris about n mm. long, 15 mm. wide and 13 mm thick. Shell outline oval, brachial valve convex, slightly inflated, with well-defined median fold. Pedicle valve less convex with shallow sulcus broadening anteriorly. Foramen medium sized to small. Beak-ridges distinct, interarea fairly long. Orna- ment varying from fine to coarse costae.

LECTOTYPE. C. schloenbachi was first described by Davidson (1874 : 59) who included three specimens which he had previously described and figured (1852 : 92, pi. 12, figs. 28-30) as varieties A and B of Rhynchonella depressa (]. de C. Sowerby), an Upper Aptian species. Two of these specimens (figs. 28, 29) were collected from the Cenomanian of Chardstock, Somerset, BM. 6.8215, and the third (fig. 30) from the Cenomanian of Shaftesbury, Wiltshire. Of these syntypes, the specimen from Shaftesbury (BM. 6.8216), figured by Davidson (1852, pi. 12, fig. 30) is here selected as lectotype of the species.

DESCRIPTION. Cyclothyris schloenbachi is a common fossil is the Lower Cenomanian beds of south Devon, Somerset, south Wiltshire, and Dorset. As can be seen from Davidson's original figures (1852, pi. 12, figs. 28-30) the ornament varies from fine, subangular to strong, coarse costae. Davidson himself (1874 : 59) noted this varia- tion and stated that intermediate forms were commonly found with the extreme forms.

The median fold is better developed or more distinct on specimens with finer costae and is often replaced in the coarser costate forms by a slight sulcation of the brachial valve.

Bifurcation of the costae is a fairly common feature of the young coarsely costate forms. Both variants occur with intermediate forms in the same beds at Chardstock in Somerset, Beer Head, Devon, and Pinhay Cliff, Dorset.

Because of its comparatively small dimensions C. schloenbachi cannot easily be confused with other known Cyclothyris species. It is distinguished from the somewhat similar C. depressa. by its oval outline, less produced beak, smaller foramen and better developed or deeper sulcus in the pedicle valve.

DISTRIBUTION. In England, C. schloenbachi appears to be confined to the Lower Cenomanian beds of south Devon, Dorset, Somerset and Wiltshire. A slightly larger form of the same species occurs in the Lower Cenomanian beds of Vivautier in the department of Orne, France and is represented in the Davidson Collection, British Museum (Natural History) by fifteen specimens numbered 6.11917. These specimens show variations identical with those of the English forms.

Cyclothyris lepida sp. n.

(PI. 4, fig. 10)

DIAGNOSIS. Cyclothyris about 22 mm. long, 32 mm. wide and 16 mm. thick. Shell biconvex, transversely oval in outline. Brachial valve with poorly developed median

56 THE BRACHIOPOD GENUS CYCLOTHYRIS

fold. Pedicle valve with broad shallow sulcus. Both valves ornamented by about 60-65 fine rounded costellae (21 per 10 mm.) with 20 on the fold and about 22 in the sulcus. Anterior contour lenticular. Linguiform extension trapezoidal, moderately developed. Beak prominent with large foramen.

HOLOTYPE. SM. 6.25683 from the Upper Aptian, Brickhill, Buckinghamshire in the collections of the Sedgwick Museum, Cambridge.

Dimensions of holotype. 26 mm. long, 33 mm. wide and 16 mm. thick.

PARATYPES. Twenty-two specimens from the type locality in the Sedgwick Museum SM. 6.25682, 6.25684-87, 6.25689-702, 6.25706-08. Also 40 specimens from the same locality and horizon in the 6ritish Museum (Natural History), 6.25546, 6.25547, 5.25549.

DESCRIPTION. C. lepida is a medium-sized Cyclothyris with a characteristic orna- ment of fine radiating costellae originating from the umbones of each valve. The absence of any prominent growth-lines gives the species a neat appearance. The beak is strong and slightly incurved. An extensive interarea is bounded by distinct beak-ridges. The foramen is large and the deltidial plates well exposed.

Internal characters. As for genus.

REMARKS. This species can be distinguished from others of Cyclothyris mainly by its distinctly oval outline, fine costellae, regular anterior commissure, moderately developed but well-marked median fold on the brachial valve, trapezoidal linguiform extension and absence of marked growth-lines. It occurs with C. antidichotoma (6uvignier) at 6rickhill but its ornament shows none of the characteristics of this species. It is probably the species referred to by authors as Rhynchonella lata d'Orbigny (1847 : 21) from the Neocomian of France.

6ecause if its regular outline, well-marked median fold and absence of prominent growth-lines, C. lepida is grouped with C. depressa and C. schloenbachi.

DISTRIBUTION. C. lepida appears to be confined to the Upper Aptian of 6rickhill, 6uckinghamshire.

Cyclothyris levis sp. n.

(PI. 4, fig- 9)

DIAGNOSIS. Cyclothyris about 20 mm. long, 24 mm. wide and 12 mm. thick. Shell biconvex, distinctly subtriangular in outline. No median fold developed on brachial valve. Shallow, broad sulcus developed anteriorly in pedicle valve. 6oth valves covered by about 100 very fine capillae (48 per 10 mm.). 6eak short, massive, foramen small. 6eak-ridges distinct. Interarea small. Deltidial plates not well exposed.

HOLOTYPE. 66.41493 in 6ritish Museum (Natural History) from the Lower Albian (L. tardefurcata Zone) of the Shenley Limestone, Leighton 6uzzard, 6edford- shire. Dimensions of holotype are : 22 mm. long, 27 mm. wide and 14 mm. thick.

PARATYPES. Sixty-one specimens in 6ritish Museum (Natural History) registered Nos. 6.26541, 6.26542, 6.26595. .

DESCRIPTION. In general outline this species resembles C. latissima but has a much more inflated brachial valve. A broad, shallow sulcus develops late in the

THE BRACHIOPOD GENUS CYCLOTHYRIS 57

pedicle valve giving rise to a low broadly arcuate anterior commissure. The short, slightly incurved beak is sharp and massive with a small circular foramen. Distinct beak-ridges define a small interarea. Faint concentric growth-lines are seen on both valves and appear more distinct towards the anterolateral margins.

Internal characters. As for genus.

REMARKS. C. levis is distinguished from other Cyclothyris species by its extremely fine, rounded capillae, short massive beak, absence of median fold in the brachial valve and poorly developed sulcus in the pedicle valve. It can be distinguished from C. lepida sp. n. mainly by its general subtriangular outline, fine capillae, absence of median fold, shorter more massive beak, less extensive interarea, poorly exposed deltidial plates and broad arcuate anterior commissure. Although resembling C. latissima in general outline it can be distinguished from this species by its less extensive interarea, less produced beak, finer ornament of capillae, less marked growth-lines and broader arcuate anterior commissure.

DISTRIBUTION. Cyclothyris levis is confined to the Lower Albian and is a common fossil in the limestone lenticles (L. tardefurcata Zone) at Leighton Buzzard, Bedford- shire.

Cyclothyris scaldisensis (d'Archiac) (PI. 4 fig. i)

1846 Terebratula scaldisensis d'Archiac, p. 330, pi. 21, fig. n.

EMENDED DIAGNOSIS. Cyclothyris about 24 mm. long, 32 mm. wide and 16 mm. thick. Shell biconvex, oval to subtriangular in outline, brachial valve with broad incipient median fold. Broad flattened median sulcus in pedicle valve. Umbo short, massive, slightly incurved. Foramen large, circular. Deltidial plates well exposed. Costae fine, rounded, numbering about 68 on each valve (12 per 10 mm.) with 15-18 on the fold and a corresponding number in the sulcus.

HOLOTYPE. The specimen used by d'Archiac in his description of the species was stated to have been collected from the Tourtia of Belgium. It is not certain whether this specimen is still extant and enquiries are still being made. Several well-preserved specimens from the Tourtia of Belgium are to be found in the Davidson Collection and in the general collections of the British Museum (Natural History). Two good examples of this species are from Tournai and are registered 6.1889, 66.41492. Another specimen, larger than the dimensions given for the typical form, is figured here on PI. 4, fig. i.

DESCRIPTION. C. scaldisensis is medium sized, characteristically oval to broadly subtriangular in outline. The brachial valve is convex and slightly inflated posteriorly with a very faintly developed median fold. The pedicle valve is convex in the umbonal region but develops a shallow sulcus which broadens anteriorly. The linguiform extension is moderately developed giving rise to a low broad, arcuate anterior commissure. Both valves are ornamented by about 65-68 fairly fine, rounded costae radiating from the umbones. Faint lamellar growth-lines are seen at about half and again at two-thirds the distance from the beak to the anterior margin. They tend to become more prominent anteriorly. The short umbo is massive with a large circular

58 THE BRACHIOPOD GENUS CYCLOTHYRIS

foramen and well-exposed deltidial plates. The beak-ridges are distinct and define a faintly concave extensive interarea.

This is probably the least variable of all species of Cyclothyris. Its characteristically fine, rounded costae and faint concentric growth-lines make it easily distinguishable from C. difformis, with which it is often associated. It differs from C. latissima, from which it was most probably developed, by its less prominent growth-lines, longer or more extensive interarea and less incurved beak.

FIG. 9. Fourteen transverse serial sections through the umbonal part of Cretirhynchia norvicensis Pettitt from the Upper Chalk (mucronata Zone), Mousehold Pit, Norwich. BM. 6.25079. x 2.

DISTRIBUTION. Apart from the area of its original description in the Lower Ceno- manian, Tourtia, of Belgium, the species is recorded from the Lower Cenomanian of Honfleur, Cap la Heve and Fecamp, Normandy and from a similar horizon in the Munster basin at Essen, Germany. It also occurs, though not commonly, in the Lower Cenomanian beds of Wiltshire, and the south Devon coast.

Genus BURRIRHYNCHIA nov.

DIAGNOSIS. Small to medium biconvex rhynchonellidae. Usually elongate- triangular in general outline. Umbo massive, suberect ; beak-ridges rounded.

THE BRACHIOPOD GENUS CYCLOTHYRIS

59

Foramen small, circular, hypothyrid. Deltidial plates disjunct, cyclothyrid. Anterior commissure with broad trapezoidal linguiform extension Faint fold on brachial valve. Hinge plates narrow, ventrally arched. Median septum strong, persistent. Ornament of fine, rounded costellae (more than 50 on each valve).

TYPE SPECIES. " Rhynchonella " leightonensis Walker, 1903.

HOLOTYPE. From Lower Albian (L. tardefurcata Zone), Shenley Hill, Leighton Buzzard, Bedfordshire, No. GSM. 51279 in the Geological Survey Museum.

FIG. 10. A series of thirteen serial sections through the umbonal part of Burrirhynchia cantabrigensis (Davidson) from the Upper Aptian of Upware, Cambridge. B.M. B.2574Q. x 2.

REMARKS. The genus differs from Cyclothyris in its more elongate-triangular outline, strong persistent median septum, small foramen, rounded beak-ridges, and narrow hinge-plates which are not terminally divided. In transverse outline it resembles Sulcirhynchia Burri (1953) from the Swiss Neocomian, from which it may have been developed. It can be distinguished from this genus, however, by its stronger, more persistent, median septum, narrower, less acutely ventrally deflected hinge-plates, shorter, less deeply inserted hinge-teeth and more clearly defined inner and outer socket-ridges.

Burrirhynchia almost certainly gave rise to Cretirhynchia Pettitt, 1950, from the Upper Chalk but is distinguished from it by its subparallel dental lamellae, disjunct

60 THE BRACHIOPOD GENUS CYCLOTHYRIS

deltidial plates, poorly defined interarea and absence of bifurcation of costellae and thicker, less clearly defined hinge-plates.

RANGE. Upper Aptian to Lower Albian.

SPECIES ASSIGNED. " R." leightonensis Walker, " R." cantabrigensis Davidson, " R." gibbsiana (]. de C. Sowerby), " R." bertheloti d'Orbigny. " R." tripartita Pictet.

MATERIAL AND LOCALITIES. One hundred and sixty specimens of B. leightonensis (Walker) from the Lower Albian (L. tardefurcata Zone), Shenley Hill, Leighton Buzzard, Bedfordshire (6.26524-28, 6.26595), 57 specimens of B. cantabrigensis (Davidson) from the Upper Aptian, of Upware, Cambridge and 85 specimens of the same species from Brickhill, Buckinghamshire and one specimen of " R" gibbsiana (J. de C. Sow.) from Folkestone, Kent, all in the British Museum (Natural History).

CONCLUSION

Although, externally, Cyclothyris shows considerable variation both in size, outline and ornament, internally it remains fairly constant. Within certain limits internal variation can be confined to the development of the hinge-plates, dental lamellae and the septum in the brachial valve. In the typical form from the Upper Aptian the dental lamellae are postero-anteriorly shorter than those of the Albian and Cenomanian forms and the hinge-plates in the Upper Aptian and Albian forms tend to be more acutely deflected towards the ventral valve than in the Cenomanian species, though this may be a variable character.

Some authors, such as Makridin (1955) and Dacque (1934) have suggested that the genus ranges from the Upper Jurassic to Cretaceous. Their definition of the genus is most probably based on Central European material which may have con- tained early ancestral forms.

The Neocomian genus Lepidorhynchia Burri (1956) certainly has both external and internal characters in common with Cyclothyris. The cyclothyrid deltidial plates are already evident and the ornament of subangular costae shows a tendency to marginal dichotomy, a character observed in very young specimens of C. latissima from Faringdon. Also, in Lepidorhynchia, are seen the ventrally curved and termin- ally divided hinge-plates which, when further developed in Cyclothyris, form the main distinguishing characters allowing the genus to be separated from Sulcirhynchia and Lamellaerhynchia. Both these genera, however, have a great deal in common with Cyclothyris and have obviously been developed from the same original stock.

It was at first thought that Cyclothyris gave rise to the Upper Cretaceous genus Cretirhynchia but, in the light of present knowledge, this theory is no longer tenable. In his description of the genus Cretirhynchia, Pettitt (1950) remarked on the differences between his genus from the Upper Chalk, and the Lower Cretaceous genus Cyclothyris. In the same work (p. n, text-fig. 4) he figured a series of serial sections of the type- species C. plicatilis (J. Sowerby) from Northfleet, Kent showing the strong converging dental lamellae, short hinge-plates persistent septum and broad radulifer crura. Recently, the writer, has prepared several serial sections of other species of Cretirhyn- chia from Norfolk and Kent which compare favourably with Pettitt's illustrations. These sections show quite clearly that Cretirhynchia is not a direct development of

THE BRACHIOPOD GENUS CYCLOTHYRIS 61

Cyclothyris but is closely related to early Cretaceous forms represented by the species " Rhynchonella " cantabrigensis Davidson from Upware and Brickhill and " R." leightonensis Walker from the Shenley Limestone. Both these species are here referred to Burrirhynchia gen. nov.

A comparison between the serial sections of Burrirhynchia cantabrigensis from Upware (Text-fig. 10) and Cretirhynchia norvicensis Pettitt from Norfolk (Text-fig. 9) shows that the two have much in common. Neither species has a pedicle collar ; the outline in transverse section is similar ; both have narrow thickened hinge-plates. The median septum in the brachial valve of both forms persists for well over one half the length of the shell. In addition the broad radulifer crura are given off dorsally from similarly shaped crural bases. Externally also the two forms are much alike. Both have a short, massive umbo with small foramen and ornament of fine, rounded costae. Neither species shows any of the distinguishing characters of Cyclothyris nor is there any tendency to asymmetry of the anterior margin, a common feature of some Cyclothyris species.

It is probable, therefore, that Cretirhynchia developed from such early Cretaceous forms as Burrirhynchia cantabrigensis and B. leightonensis which marked the beginning or early stages and C. norvicensis the last or later stages of its evolution. Both B. cantabrigensis and B. leightonensis are closely related to Sulcirhynchia Burri, from the Neocomian of Switzerland.

Cyclothyris probably died out in the Upper Cenomanian with C. compressa (Valen- ciennes in Lamarck), though Turonian species such as " Rhynchonella " vespertilio (Brocchi) which may have been developed from C. compressa and " R." elegans Hanstein, from the Ciply Chalk, have still to be investigated.

ACKNOWLEDGMENTS

I am greatly indebted to Dr. E. I. White, F.R.S., Keeper of Palaeontology, British Museum (Natural History) for permission to work on the collections in his department and to Dr. H. M. Muir-Wood for her kind help and encouragement, and for reading the manuscript.

My thanks are also due to Dr. F. Burri, Basel ; to Mme. A. Schnorf, Musee Geolo- gique, Lausanne, Switzerland ; to Mr. A. G. Brighton and Dr. Colin Forbes, Sedgwick Museum, Cambridge ; to Mr. K. J. Evans, King's College, London and to Dr. VV. T. Dean and Mr. F. M. Wonnacott, British Museum (Natural History), London.

REFERENCES

ACER, D. V. 1958. A Monograph of the British Liassic Rhynchonellidae , 2 : 51-84, pis. 1-3.

[Mon. Palaeont. Soc., London.] D'ARCHIAC, A. 1847. Rapport sur les fossiles du Tourtia. Mem. Soc. geol. Fr., Paris (2)

2 : 291-351, pis. 13-25. BARROIS, C. 1875. Sur le Gault et sur les couches entre lesquelles il est compris dans le

bassin de Paris. Ann. Soc. geol. Nord, Lille, 2 : 1-63.

BROCCHI, G. 1814. Conchiologia fossile subapennina, 2 : 241-712, pis. 1-16. Milan. BRONGNIART, A. 1822. In Cuvier, G. & Brongniart, A. Description geologique des environs de

Paris, iv + 428 pp., n pis. Paris.

62 THE BRACHIOPOD GENUS CYCLOTHYRIS

BUCKMAN, S. S. 1906. Brachiopod Nomenclature. Ann. Mag. Nat. Hist., London (7) 18 :

32-327-

— 1918. Brachiopoda of the Namyau Beds, Northern Shan States, Burma. Palaeont. Indica, Calcutta (N.S.) 3, 2 : 1-299, pis. 1-21.

BURRI, F. 1956. Die Rhynchonelliden der Unteren Kreide (Valanginien-Barremien) im

westschweizerischen Juragebirge. Eel. geol. Helv., Lausanne, 49 : 600-701, pis. 1-15. CASEY, R. 1961. The stratigraphical palaeontology of the Lower Greensand. Palaeontology,

London, 3 : 487-621, pis. 77-84. CAYEUX, L. 1949. Essai de classification des mollusques brachiopodes de 1'etage cenomanien

de la region. Bull. Soc. geol. Normandie, Le Havre (N.S.) 3 : 1-4. CLERC, M. & FAVRE, J. 1918. Catalogue illusive de la collection Lamarck, Part I. 117 pis.

Paris. COOPER, G. A. 1955. New Cretaceous Brachiopoda from Arizona. Smithson. Misc. Coll.,

Washington, 131, 4 : 1-18, pis. 1-4. CORROY, G. 1925. Le Neocomien de la bordure orientale du Bassin de Paris. Bull. Soc. Sci

nat. Nancy (4) 2 : 1-171. DACQUE, E. 1934. Wirbellose des Jura. In Gurich, G. Leitfossilien, 7 : 582 pp., 24 pis.

Berlin. DALL, W. H. 1877. Index to the names which have been applied to subdivisions of the Class

Brachiopoda. Bull. U.S. Nat. Mus., Washington, 8 : 1-87. DAVIDSON, T. 1852-54. A Monograph of British Cretaceous Brachiopoda, 2. 117 pp., 12 pis.

[Mon. Palaeont. Soc., London.]

— 1874. A Monograph of the British Fossil Brachiopoda, 4, i. Supplement to the Recent, Tertiary, and Cretaceous Species. 72 pp., 8 pis. [Mon. Palaeont. Soc., London.]

DEFRANCE, M. J. L. 1828. Terebratula deformis Lamk. Diet. Sci. nat., Paris, 53 : 160. FACE, G. 1935. Rhynchonelles du Cretace Superieur des Charentes. Bull. Soc. geol. Fr.t

Paris (5) 4:433-441, pi. i. FITTON, J. 1836. Observations on some of the strata between the Chalk and the Oxford

Oolite in south-east of England. Trans. Geol. Soc. Lond. (2) 4 : 335-349, pis. 11-23. GEINITZ, H. B. 1872. Das Elthalgebirge in Sachsen. Palaeontographica, Stuttgart, 20 :

147-207, pis. 36-45.

HANSTEIN, R. VON. 1879. Brachiopoden der oberen Kreide von Ciply. 58 pp. Bonn. HERTLEIN, L. G. & GRANT, U. S. 1944. The Cenozoic Brachiopoda of Western North America.

Univ. Calif. Publ. Math. Phys. Sci., Berkeley, 3. vi + 236 pp., 21 pis. IMLAY, R. 1937. Lower Neocomian fossils from the Miquihuana region, Mexico. /. Paleont.,

Menasha, 11 : 552-574, pis. 1-13. JUKES-BROWNE, A. J. 1900. Cretaceous Rocks of Britain, i. Gault and Upper Greensand of

England, x + 499 Pp- [Mem. Geol. Surv. U.K.] London. - & HILL, W. 1896. A Delimitation of the Cenomanian ; being a comparison of the

corresponding Beds of South-Western England and Western France. Quart. J. Geol.

Soc., Lond., 52 : 99-177.

LAMARCK, J. P. B. 1819. Histoire naturelle des animaux sans vertebres, 6, i : 1-343. Paris. MAKRIDIN, V. P. 1955. Some Jurassic Rhynchonellids of the European part of USSR.

Zap. Geol. Fak. Kharkov State Univ., 12 : 81-91. [In Russian]. M'Cov, F. 1844. A synopsis of the characters of the Carboniferous Limestone fossils of Ireland.

viii + 207 pp., 29 pis. Dublin. MEYER, C. J. A. 1874. On Cretaceous rocks of Beer Head and adjoining cliff-sections, and

on the relative horizons therein of the the Warminster and Blackdown fossiliferous deposits.

Quart. J. Geol. Soc. Lond., 30 : 369-393. MIDDLEMISS, F. A. 1959. English Aptian Terebratulidae. Palaeontology, London, 2 : 94-142,

pis. 15-18. MuiR-WooD, H. M. 1934. On the internal structure of some Mesozoic Brachiopoda. Philos.

Trans., London (B) 223 no. 505 : 511-567, pis. i, 2.

THE BRACHIOPOD GENUS CYCLOTHYRIS 63

MuiR-WooD, H. M. 1955. A History of the Classification of the Phylum Brachiopoda. 124 pp. British Museum (Nat. Hist.), London.

— & COOPER, G. A. 1960. Morphology, Classification and life habits of the Productoidea (Brachiopoda). Mem. Geol. Soc. Amer., Rochester, N.Y., 81 : xi -f- 447 pp., 135 pis.

OWEN, E. F. 1955. The use of sugar solution in the differentiation of the internal structures of Upper Chalk Brachiopods. Proc. Geol. Ass. Lond., 66 : 369-370.

1956. The Lower Cretaceous Brachiopods " Rhynchonella " gibbsiana (J. de C. Sowerby)

and Sulcirhynchia hythensis sp. nov. Ann. Mag. Nat. Hist., London (12) 9 : 164-172, pi. i.

— 1960. A Note on " Rhynchonella " sulcata (Parkinson) from the Lower Cretaceous of Great Britain. Ann. Mag. Nat. Hist., London (13) 2 : 248-256, pi. i.

ORBIGNY, A. D'. 1848-51. Terrains cretaces. Paleontologie francaise, 4: 1-390, pis. 490-599.

Paris. PETTITT, N. E. 1950. Rhynchonellidae of the British Chalk, I. 26 pp., 2 pis. [Mon.

Palaeont. Soc., London.] - 1954. Rhynchonellidae of the British Chalk, II. 26 pp, i pi. [Mon. Palaeont. Soc.,

London] . PICTET, F. J. 1872. Description des fossiles du terrain cretac6 des environs de Sainte-Croix, 5.

Mater. Paleont. suisse, Geneve (6) 1 : 1-158, pis. 195-208.

— & Roux, W. 1847-53. Mollusques fossiles des gres verts de Geneve. 558 pp., 51 pis. Geneve. QUENSTEDT, F. A. 1882. Handbuch der Petrefactenkunde. viii -f 1239 pp., Tubingen (esp.

p. 696). RZHONITSKAYA, M. A. 1959- Systematics of the Rhynchonellids. Pal. J. Akad. Nauk.

SSSR., 1 : 25-36. [In Russian]. SCHLOENBACH, U. 1867. Uber die Brachiopoden der norddeutschen Cenoman-Bildungen.

Geogn. Paldont. Beitr. (E. W. Benecke), Miinchen, 1 : 399-506, pis. 21-23. SCHUCHERT, C. 1913. Brachiopoda. In Zittel, K. A. von, edited by Eastman, C. R. Textbook

of Palaeontology, 1 : 355-420, figs. 526-636. 2nd edit. London. SHARPE, D. 1854. On the age of the fossiliferous sands and gravels of Farringdon and its

neighbourhood. Quart. J. Geol. Soc. Lond., 10 : 176-198, pis. i, 2. SOWERBY, J. 1812-15. Mineral Conchology of Great Britain, 1. vii + 234 pp., 102 pis.

London.

— 1818-21. Mineral Conchology of Great Britain, 3. 184 pp., pis. 204-306. London. SOWERBY, J. DE C. 1836. In Fitton, J. Observations on some of the strata between the

Chalk and the Oxford Oolite in the south-east of England. Trans. Geol. Soc. Lond. (2) 4 :

335-349, pis. 11-23. SPATH, L. F. 1926. On the zones of the Cenomanian and Uppermost Albian. Proc. Geol. Ass.

Lond., 37 : 420-432. THOMSON, J. A. 1927. Brachiopod morphology and genera (Recent and Tertiary). N.Z.

Board Sci. Art. Manual, 7 : vi + 338 pp., 2 pis. Dominion Museum, Wellington. WRIGHT, C. W. & E. V. 1951. A survey of the fossil cephalopoda of the Chalk of Great Britain.

41 pp. [Mon. Palaeont. Soc., London.]

PLATE 4

FIGS. ia-c. Cyclothyris scaldisensis (d'Archiac). Tourtia, Gussignies, Belgium. BM. B.I 1965.

FIGS. za-c. Cyclothyris dimidiata (J. Sowerby) = C. difformis. Cenomanian, Halldown, south-east Devon. BM. 6.61466.

FIGS. 3«-c. Cyclothyris antidichotoma (Buvignier). Lower Albian, Shenley Hill, Leigh ton Buzzard, Bedfordshire. BM. 66.41495.

FIGS. ^a-c. Cyclothyris antidichotoma (Buvignier). Lower Albian, Goudiniere, Grand St. Bernard, Savoie, France. BM. 66.41486.

FIGS. $a-c. Cyclothyris antidichotoma (6uvignier). Upper Aptian, 6rickhill, 6uckingham- shire. 6M. 66.41490.

FIGS. 6a-c. Cyclothyris antidichotoma (6uvignier). Upper Aptian, Upware, Cambridge. 6M. 6.27264.

FIGS. ja-c. Cyclothyris latissima (J. de C. Sowerby). Upper Aptian, Faringdon, 6erkshire. 8M. 66. 41494.

FIGS. Sa-c. Cyclothyris latissi ma (J. deC. Sowerby). Lectotype. Upper Aptian, Faringdon, 6erkshire. 6M. 6.61499.

FIGS. ga-c. Cyclothyris levis sp. n. Holotype. Lower Albian, Shenley Hill, Leigh ton 6uzzard, 6edfordshire. 6M. 66.41493.

FIGS. ioa-c. Cyclothyris lepida sp. n. Holotype. Upper Aptian, 6rickhill, 6uckingham- shire. Sedgwick Museum Coll. 6.25683.

FIGS. na-c. Cyclothyris depressa (J. de C. Sowerby). Lectotype. Upper Aptian, Faring- don, 6erkshire. 6M. 6.61468.

FIGS. I2a-c. Cyclothyris schloenbachi (Davidson). Lectotype. Lower Cenomanian, Shaftes- bury, Wiltshire. 6M. 6.8216.

FIGS. i$a-c. Cyclothyris schloenbachi (Davidson). Coarsely costate variant from Chard- stock, Somerset. 6M. 6. 8215.

All figures at natural size unless otherwise stated. 6M. — 6ritish Museum (Natural History).

4 JUN196?

Bull. B.M. (N.H.) Geol. 7, 2

PLATE 4

6a

PLATE 5

FIGS. la-c. Cyclothyris difformis (Valenciennes in Lamarck). Cenomanian, Warminster, Wiltshire. Typical form. B.M. no. 45336.

FIGS. 2a-c. Cyclothyris difformis (Valenciennes in Lamarck) . Lower Cenomanian, Wilming- ton, south Devon. BM. 36.41433.

FIGS. 3«-c. Cyclothyris difformis (Valenciennes in Lamarck). Lower Cenomanian, Cap le Heve, near Le Havre, Normandy BM. 6.82754.

FIGS. 4«-c. Cyclothyris difformis (Valenciennes in Lamarck). Lower Cenomanian, Wilming- ton, south Devon. BM. 66.15292.

FIGS. 5a— c. Cyclothyris difformis (Valenciennes in Lamarck). Tourtia, Tournai, Belgium. BM. 66.41476.

FIGS. 6a-c. Cyclothyris difformis (Valenciennes in Lamarck). Cenomanian, Essen, Germany. Similar variant to fig. 5 from Belgium. 6M. 66.41473.

FIGS. ja-c. Cyclothyris difformis (Valenciennes in Lamarck). Lower Cenomanian, War- minster, Wiltshire. 6M. 6.8301.

FIGS. Sa-c. Cyclothyris compressa (Valenciennes in Lamarck). Upper Cenomanian, Le Mans, Sarthe, France. BM. 66.41489.

Bull. B.M. (N.H.) Geol. 7, 2

PLATE 5

la

Ic

2c

2a

8c

THE TRILOBITES OF THE CARADOC

SERIES IN THE CROSS FELL INLIER

OF NORTHERN ENGLAND

W. T. DEAN

BULLETIN OF THE BRITISH MUSEUM (NATURAL HISTORY)

GEOLOGY Vol. 7 No. 3

LONDON: 1962

THE TRILOBITES OF THE CARADOC SERIES IN THE CROSS FELL INLIER OF NORTHERN

ENGLAND

BY

WILLIAM THORNTON DEAN

Pp. 65-134 ; Pis. 6-1 8 ; 5 Text-figures

BULLETIN OF THE BRITISH MUSEUM (NATURAL HISTORY)

GEOLOGY Vol. 7 No. 3

LONDON: 1962

THE BULLETIN OF THE BRITISH MUSEUM (NATURAL HISTORY), instituted in 1949, is issued in five series corresponding to the Departments of the Museum, and an Historical Series.

Parts will appear at irregular intervals as they become ready. Volumes will contain about three or four hundred pages, and will not necessarily be completed within one calendar year.

This paper is Vol. 7, No. 3 of the Geological (Palaeontologicai) series.

Trustees of the British Museum 1962

PRINTED BY ORDER OF THE TRUSTEES OF THE BRITISH MUSEUM

Issued August 1962 Price Forty-two Shillings

THE TRILOBITES OF THE CARADOC SERIES IN THE CROSS FELL INLIER OF NORTHERN

ENGLAND

By WILLIAM THORNTON DEAN

Page I. INTRODUCTION AND ACKNOWLEDGMENTS ...... 69

II. STRATIGRAPHICAL SUMMARY ........ 69

III. SYSTEMATIC DESCRIPTIONS ........ 72

Family Raphiophoridae Angelin . . . . . .72

Lonchodomas swindalensis sp. nov. ..... 72

Lonchodomas pennatus (La louche) ..... 78

Family Trinucleidae Hawle & Corda ..... 79

Subfamily Cryptolithinae Angelin ...... 79

Broeggerolithus nicholsoni (Reed) ..... 79

Broeggerolithus melmerbiensis sp. nov. . . . . .81

Broeggerolithus cf. transiens (Bancroft) .... 82

Broeggerolithus sp. . . . . . . .83

Onnia gracilis (Bancroft) ....... 84

Onnia superba (Bancroft) pusgillensis Dean .... 84

Subfamily Tretaspidinae Whittington ..... 85

Tretaspis cf. ceriodes donsi St0rmer ..... 85

Tretaspis convergens Dean . . . . . . .85

Tretaspis kiaeri St0rmer radialis Lament .... 86

Tretaspis kiaeri St0rmer duftonensis Dean . . . .86

Family Cheiruridae Salter ....... 86

Subfamily Cyrtometopinae Opik ...... 86

Pseudosphaerexochus cf. octolobatus (M'Coy) .... 87

Family Encrinuridae Angelin ....... 88

Subfamily Encrinurinae Angelin ...... 88

Encrinurus sp. ........ 88

Subfamily Dindymeninae Pfibyl ...... 89

Dindymene duftonensis sp. nov. ...... 89

Dindymene sp. ......... 90

Subfamily Cybelinae Holliday . . . . . .91

Atractopyge scabra sp. nov. . . . . . .91

Atractopyge? sp. ........ 93

Paracybeloides cf. girvanensis (Reed) ..... 94

Paracybeloides sp. ........ 95

Family Dalmanitidae Reed ....... 95

Subfamily Dalmanitinae Reed ...... 95

Dalmanitina mucronata (Brongniart) matutina subsp. nov. . 95 Subfamily Acastinae Delo . . . . . . -97

Kloucekia (Phacopidina) apiculata (M'Coy) ... 97

Duftonia lacunosa Dean ....... 97

GEOL. 7, 3. 3

68 THE TRILOBITES OF THE CARADOC SERIES

Page

Family Pterygometopidae Reed ...... 98

Subfamily Pterygometopinae Reed ..... 98

Calyptaulax planiformis sp. nov. ..... 98

Estoniops alifrons (M'Coy) ...... 100

Subfamily Chasmopsinae Pillet . . . . . .104

Chasmops cf. extensa (Boeck) . . . . . .104

Chasmops aff. maxima (Schmidt) ..... 105

Chasmops sp. ......... 105

Family Homalonotidae Chapman . ; . . . . .106

Brongniartella minor (Salter) . . . . . .106

Brongniartella ascripta (Reed) . . . . . .106

Brongniartella bisulcata (M'Coy) . ' . . . . . 108

Brongniartella depressa sp. nov. ...... 108

Brongniartella aff. platynota (Dalman) . . . .no

Family Calymenidae Burmeister . . . . . .in

Flexicalymene cf. caractaci (Salter) . . . . .114

Onnicalymene onniensis (Shirley) . . . . .115

Onnicalymene laticeps (Bancroft) . . . . .115

Diacalymene cf. marginata Shirley . . . . .116

Gravicalymene jugifera sp. nov. . . . . . .116

Family Dimeropygidae Hupe . . . . . . .118

Toernquistia aff. reedi Thorslund . . . . .118

Family Illaenidae Hawle & Corda . . . . . .120

Stenopareia? sp. . . . . . . . .120

Family Lichidae Hawle & Corda . . . . . .120

Subfamily Homolichinae Phleger . . . . . .120

Conolichas melmerbiensis (Reed) . . . . .120

Platylichas cf. laxatus (M'Coy) . . . . . .121

Family Odontopleuridae Burmeister . . . . . .122

Primaspis semievoluta (Reed) ...... 122

Odontopleurid gen. et sp. ind. ...... 123

Family Otarionidae R. &. E. Richter . . . . .123

Otarion sp. ......... 123

Family Proetidae Salter . . . . . . . .124

Subfamily Proetidellinae Hupe . . . . . .124

Proetidella? marri sp. nov. ...... 124

Family Remopleurididae Hawle & Corda . . . . .127

Remopleurides spp. ........ 127

IV. STRATIGRAPHICAL DISTRIBUTION AND RELATIONSHIPS OF THE TRILOBITES 128 V. REFERENCES .......... 130

SYNOPSIS

The trilobites known from the Caradoc Series in the Cross Fell Inlier are described and figured, many of them for the first time. They comprise fifty species and subspecies, assigned to twenty-eight genera and fifteen families. The relationships of the trilobites to those of other successions is reviewed. In the Longvillian and Marshbrookian Stages the fauna is of Anglo- Welsh type with occasional Baltic elements, but in subsequent stages the affinities with corres- ponding Norwegian and Swedish faunas becomes marked, reaching a maximum in the Pusgillian Stage.

THE TRILOBITES OF THE CARADOC SERIES 69

I. INTRODUCTION AND ACKNOWLEDGMENTS

THE name Cross Fell Inlier is applied by geologists to the elongated area of Lower Palaeozoic rocks, a few miles north of Appleby, Westmorland, which extends in a south-south-easterly direction between the Carboniferous strata of the Pennines and the Permo-Trias of the Vale of Eden. The geological structure of the area is of great complexity and has been described by Shotton (1935). The disposition of the principal outcrops of Caradoc strata is shown in Text-fig, i.

Although the first detailed stratigraphical accounts, accompanied by faunal lists, of the Caradoc Series in the Inlier were given during the last century by Harkness & Nicholson (1878), and Nicholson & Marr (1891), it was not until 1907 and 1910 that any figures and descriptions of trilobites were published. In those years Reed described four new species, Lichas melmerbiensis , Acidaspis semievoluta, Homa- lonotus ascriptus and Trinudeus nicholsoni, from strata which he called Dufton Shales at the road-section near Melmerby, as well as listing several other species from the same locality.

Bancroft (1933) listed a few Shropshire species of trilobites and brachiopods from the Inlier but it was not until 1936 that another trilobite was illustrated, when Shirley figured a specimen of Flexicalymene onniensis, a south Shropshire species, from an unspecified locality and horizon within the Dufton Shales of Pus Gill, near Dufton. In 1948 Bancroft's manuscript notes on the Cross Fell succession, in- cluding locality maps of Swindale Beck and part of Pus Gill, were published posthumously by Lament, who added photographs of certain Shropshire specimens but figured none from the Inlier.

Since then a new genus, Duftonia, has been described from the Dufton Shales by the writer (Dean, 1959) who, in a later paper (19590;), discussed the detailed strati- graphy of the area and gave faunal lists. More recently some of the Trinucleidae occurring in the upper part of the succession have been described and figured (Dean, 1961). The present work aims at describing and figuring all the trilobites listed and discussed in the foregoing papers. Extensive collections of trilobites have been made during field-work financed in part by grants from the Gloyne Fund of the Geological Society of London, and I am grateful to the Council of the Society for their assistance. All the material is housed in the British Museum (Natural History), London. I wish to thank the Council of the Yorkshire Geological Society for permission to reproduce the sketch-map shown in Text-fig. 4. I am indebted to Mr. A. G. Brighton for the loan of type-specimens from the Sedgwick Museum, Cambridge, to my wife for her important share of the collecting, and to Professor W. F. Whittard who has kindly read and criticized the manuscript.

II. STRATIGRAPHICAL SUMMARY

The following table represents the subdivisions of the Caradoc Series which are generally recognized today in the main portion of the Inlier, together with the equivalent faunal zones as established in the type-area of south Shropshire.

The subdivision of the strata into Corona Beds and Dufton Shales is made on lithological grounds, the former including maroon and grey mudstones and shales

7o

THE TRILOBITES OF THE CARADOC SERIES

SKETCH-MAP SHOWING THE DISTRIBUTION OF CARADOC OUTCROPS IN THE CROSS FELL INLIER [AFTER SHOTTON. 1935]

ASHGILL SERIES CARADOC SERIES

A. ALSTON ROAD

B. KNOCK-DUFTON

DISTRICT

C. HILTON BECK

D. ROMAN FELL

D.-

FIG. i.

THE TRILOBITES OF THE CARADOC SERIES

Stage PUSGILLIAN

ONNIAN

ACTONIAN MARSHBROOKIAN

U . Broeggerolithus longiceps

LONGVILLIAN

I

Zonal TrUobite

Onnia superba Onnia gracilis Onnia ? cobboldi

Platylichas laxatus Broeggerolithus transiens

Broeggerolithus globiceps

Zonal Brachiopod

Onniella broeggeri Onniella inconstans

Cryptothyris paracyclica

Onniella reuschi Dalmanella unguis Dalmanella wattsi

Kjaerina typa Kjaerina bipartita

Bancroftina typa Dalmanella indica and D. lepta Dalmanella horderleyensis ?

Lithological Subdivision

DUFTON SHALES

CORONA BEDS

with occasional limestone bands, whilst the latter comprise essentially a rather monotonous series of dark-grey mudstones and shales with bands of nodular and impure limestone which often weather to a rotten-stone or " gingerbread " rock. The Corona Beds are shown in the table to coincide with the limits of the Lower Longvillian Substage, but in fact the zone of Dalmanella indica and D. lepta is the lowest faunal horizon definitely recognized, though the underlying zone may well be represented. The topmost zone of the Lower Longvillian is represented in the highest Corona Beds and it seems likely that there is a transition to the overlying Dufton Shales, but owing to extensive faulting the lowest zone of the Upper Longvillian has not been detected throughout the greater part of the Inlier. The remainder of the succeeding Caradoc strata as found in the Shropshire type-area are, for the most part, represented in the Cross Fell Inlier, with the addition of the Pusgillian Stage. This subdivision is held to constitute the topmost part of the Caradoc Series and to pre-date any known Ashgill strata. In Swindale Beck, near Knock, the Pusgillian is followed in the succession by the Staurocephalus or Swindale Lime- stone. The junction of the two has often been assumed to be conformable, but the writer believes there is a marked stratigraphical break above the Pusgillian, and that the Limestone represents a relatively high Ashgill horizon, as it is followed at Swindale Beck by Ashgill Shales with Hirnantia sagittifera (M'Coy). South-east of Dufton the Pusgillian outcrop is separated from that of the Swindale Limestone by a small thickness of strata, equated with part of the Diacalymene Beds of Cautley, which are probably overstepped by the Limestone.

The northernmost outcrops of Caradoc strata within the Inlier occur only in the vicinity of the village of Melmerby, after which they are known as the Melmerby Beds. The rocks have been divided into an upper and lower series ; the Upper

72 THE TRILOBITES OF THE CARADOC SERIES

Melmerby Beds contain a fauna indicative of the lower zone of the Upper Long- villian Substage, an horizon which, as stated earlier, is not yet known elsewhere in the Inlier. In the field, the Lower Melmerby Beds appear to underlie the upper beds stratigraphically and are considered to be of Lower Longvillian age ; they contain abundant evidence of a Longvillian age but the zonal brachiopods of the Shropshire succession have not yet been detected and may be absent owing to the unsuitability of the environment. The rocks are mainly dark-green or maroon, blocky mudstones with occasional impure, nodular limestones. Their fauna includes a conspicuously large number of trinucleid trilobites, accompanied by common Kloucekia apiculata (M'Coy), features which readily distinguish them from the equivalent strata farther south in the Inlier, and which are more suggestive of corresponding North Welsh faunas.

No useful evidence has yet been obtained from the region to elaborate on the cor- relation between the shelly and graptolitic successions already put forward for south Shropshire (Dean, 1958 : 226). The Pusgillian, from its position above the Onnian (believed to represent the topmost Dicranograptus dingani Zone) , is equated approxi- mately with the Pleurograptus linearis Zone, and the shelly fauna suggests a correlation with Etage 4ca of southern Norway, an horizon which is itself correlated with that graptolite zone.

The fossil localities cited in the following descriptions are shown in Text-figs. 2-5. Text-fig 3 covers the well-known section of Swindale Beck, just north-east of the village of Knock ; Text-fig 2 shows Pus Gill, north-east of Dufton ; Text-fig. 4 covers the large area of east of Dufton, with the important sections of Dufton Town Sike, Billy's Beck and Harthwaite Sike ; Text-fig. 5 shows the small, isolated outcrop of the Melmerby Beds north-east of Melmerby, near the northern end of the Inlier.

III. SYSTEMATIC DESCRIPTIONS

Family RAPHIOPHORIDAE Angelin, 1854

Genus LONCHODOMAS Angelin, 1854

TYPE-SPECIES. Ampyx rostratus Sars, 1835 by subsequent designation of Bassler (1915 : 41).

Lonchodomas swindalensis sp. nov. (PL 6, figs. 2, 6, 8)

19590. Lonchodomas aff. rostratus (Sars) Dean, pp. 194, 207.

DIAGNOSIS. Lonchodomas with glabella projecting only short distance in front of fixigenae. Pygidium semi-elliptical with four pairs of pleural furrows, the first pair being the most sharply defined.

DESCRIPTION. The material is fragmentary for the most part but includes two almost whole cranidia and one small, well-preserved pygidium. Excluding the

THE TRILOBITES OF THE CARADOC SERIES

73

74

THE TRILOBITES OF THE CARADOC SERIES

FOSSIL LOCALITIES

IN SWINDALE BECK

NEAR KNOCK

FIG. 3.

THE TRILOBITES OF THE CARADOC SERIES

75

o

£

76

THE TRILOBITES OF THE CARADOC SERIES

FOSSIL LOCALITIES

71

ON

THE

ALSTON ROAD, NEAR XMELMERBY

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1+ + • ^ '* ' * i v- o _±_ _+ + +'+/+ + + -»£

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/ FAULTS DELIMITING CARADOC OUTCROP

FIG. 5.

THE TRILOBITES OF THE CARADOC SERIES 77

frontal spine, the dimensions of the cranidia, numbered respectively In. 49946 and In. 49968, are as follows : length, 5 mm., breadth, 9 mm. ; length, u mm. ; breadth, 16 mm. Dimensions of the pygidium, In. 49967, are : length, 1-5 mm., breadth, 4-5 mm. The cranidium is roughly rhomboidal in plan, produced anteriorly into a long, frontal spine, the surface of which bears fine, longitudinal striae. The glabella attains its greatest breadth at its mid-point and is bounded by almost straight axial furrows containing slot-like hypostomal pits, situated frontally. One cranidium (PI. 6, fig. 2) shows a faint median ridge extending from near the occipital furrow to the base of the frontal spine, where it is replaced by a groove ; similar grooves occur on the sides and undersurface of the frontal spine as in other species of Lonchodomas , giving rise to the fluted, quadrate cross-section characteristic of the genus. The posterior margin of the cranidium, and the pleuroccipital furrows are parallel, transversely straight except medially where, owing to a small extension of the glabella, they are convex backwards.

The pygidium is semi-elliptical in outline with a strongly-curved, steeply-declined, posterior border which carries fine, parallel terrace lines, though the latter are not visible in the photograph (PI. 6, fig. 6). The anterior margin is straight medially but curves forwards a little anterolaterally. There are four pairs of pleural furrows, the first pair being the most deeply impressed ; all are deepest anterolaterally becoming faint at, or near, the shallow axial furrows. No axial rings are visible.

HORIZON AND LOCALITIES. All the known specimens have been collected from Dufton Shales belonging to the upper half of the Upper Longvillian Substage in Swindale Beck. There they occur in association with Kjaerina geniculata Bancroft, Reuschella sp. nov. and Dolerorthis sp. The figured specimens are from localities B. 5 and B. 6, but the same form has been found also at B. 10 (see Text-fig. 3). These are the only records of Lonchodomas from the Upper Longvillian of the Anglo- Welsh area.

HOLOTYPE. In. 49968 (PI. 6, fig. 2).

PARATYPES. In. 49946 (PI. 6, fig. 8) ; In. 49967 (PI. 6, fig. 6).

DISCUSSION. The Swindale Beck species bears an obvious relationship to Lonchodomas rostratus (Sars) which has been refigured by St0rmer (1940 : 128, pi. 2, figs. 1-4). The latter species has, however, a smaller proportion of the glabella projecting in front of the fixigenae, and the pygidium of the Norwegian form, the type-specimens of which were obtained from the Ampyx Limestone (zone of Nemagraptus gracilis) near Oslo, differs also in having only one pair of well-defined, distally situated, pleural furrows, which die out before attaining the axial furrows.

Lonchodomas politus (Raymond, 1925 : 39, pi. 2, figs. 8, 9 ; Cooper, 1953 : 18, pi. 6, figs, i, 2, 5-10), from the " Upper Lenoir Limestone " of Black River age in Tennessee, has a conspicuously punctate test and a pygidium bearing seven or eight pairs of furrows, only the first of which is deeply impressed, but otherwise much resembles the Cross Fell species.

The stratigraphically younger species Lonchodomas pennatus (La Touche), discussed elsewhere in the present paper, has a relatively larger proportion of the glabella projecting in front of the fixigenae, whilst the pygidium has a less well- differentiated axis than that of L. swindalensis , and only one pair of pleural furrows.

78 THE TRILOBITES OF THE CARADOC SERIES

Lonchodomas pennatus (La Touche) (PI. 6, figs, i, 3-5, 9, 12)

1884. Ampyx pennatus La Touche, p. 57, pi. 3, fig. 56.

1891. Ampyx tetragonus Angelin : Nicholson & Marr, p. 511.

1932. Ampyx (Lonchodomas) pennatus La Touche : Reed, p. 205, pi. n, figs. 5-7.

1949. Lonchodomas pennatus (La Touche) Bancroft, p. 299, pi. 10, fig. 17.

1958. Lonchodomas pennatus (La Touche) : Dean, pp. 213, 224.

19590. Lonchodomas pennatus (La Touche) : Dean, pp. 200, 207.

1960. Lonchodomas pennatus (La Touche) : Dean, p. 82, pi. u, figs. 2, 5, 8-12.

Several cranidia agreeing in all essentials with La Touche's species have been collected from the Dufton Shales. The often indifferent preservation renders precise measurement difficult , most of the specimens being compressed vertically, but the proportions are close to those of similarly preserved Shropshire material, the length of the cranidium, measured from the base of the frontal spine to the posterior margin of the occipital ring, being slightly more or less than three-quarters of the maximum breadth. A feature not previously seen in L. pennatus but now preserved in one specimen (PL 6, fig. i) is the retrousse form of the prismatic frontal spine, which curves forwards and gently upwards from the glabella : a similar curvature is seen also in Ampyx salteri Hicks and Ampyx linleyensis (Whittard, 1955, pi. i, fig. 17 ; pi. 2, fig. 6). A few individuals have traces of a slight median ridge or carina on the glabella, and this may be either accentuated by lateral com- pression or absent altogether. A similar ridge occurs in some Shropshire specimens, but its presence varies with the state of preservation. Two probably immature pygidia from Cross Fell (PI. 6, fig. 5) are proportionately broader than the forma typica, their length : breadth radio being i : 3, but in mature pygidia this changes to about i : 2, that is to say, generally comparable with the Shropshire material.

HORIZON AND LOCALITIES. In the Knock-Dufton district Lonchodomas pennatus appears for the first time in the Onnian Stage, Onnia gracilis Zone, of Pus Gill, at localities A. 8, 9, 12 and 14. It has been found less commonly in the overlying Onnia superba Zone of Pus Gill, at localities A. 5 and 16. The ensuing Pusgillian Stage has yielded specimens at both Pus Gill, localities A. 6, 18 and 28, and Swindale Beck, locality B. 25.

DISCUSSION. La Touche's holotype was obtained from the Onnian Stage, Onnia superba Zone, in the Onny Valley of south Shropshire, in which district Lonchodomas pennatus ranges upwards from the Actonian Stage (Dean, 1960 : 83). The discoveries in the Pusgillian Stage of the Cross Fell Inlier increase the known vertical range of the species, but there is no information yet regarding its relationship to still younger forms, though there is a general resemblance to certain species of Ashgill age, for example that figured by Reed (1905 : 97, pi. 4, fig. 2) as Ampyx (Lonchodomas) cf. rostratus Sars from the Slade Beds of Haverfordwest.

Elsewhere, a small cranidium of Lonchodomas which may be conspecific with L. pennatus has been figured by Stermer (1945, pi. 2, fig. 10) as Lonchodomas aff. rostratus (Sars) from the Tretaspis Shales of Hadeland, a horizon approximately equivalent to the Pusgillian Stage. Lonchodomas carinatus (Cooper, 1953 : 17, pi. 7,

THE TRILOBITES OF THE CARADOC SERIES

79

figs. 12-17, 19-23) from the Black River Stage of Tennessee bears a strong resem- blance to L. pennatus but possesses an irregularly punctate test, and the glabella projects less far forwards in front of the fixigenae. The pygidium of L. carinatus differs in having at least four discernible axial rings.

Family TRINUCLEIDAE Hawle & Corda, 1847

Subfamily CRYPTOLITHINAE Angelin, 1854 Genus BROEGGEROLITHUS Lamont, 1935 TYPE SPECIES. Cryptolithus broeggeri Bancroft, 1929 by original designation.

Broeggerolithus nicholsoni (Reed) (PL 6, figs. 7, ii?, 14? ; PL 7, figs. 1-12)

1891. Trinucleus goldfussi Barrande ?, Nicholson & Marr, p. 509.

1891. Trinucleus seticornis Hisinger ?, Nicholson & Marr, p. 509.

1910. Tinucleus nicholsoni Reed, p. 212, pi. 16, figs. 1-9.

1912. Trinucleus nicholsoni Reed : Reed, pi. 18, fig. 6 ; pi. 19, figs. 4, 4^.

1914. Trinucleus gibbifrons M'Coy : Reed, p. 356, pi. 29, fig. 6.

1914. Trinucleus nicholsoni Reed : Reed, p. 357.

1927. Cryptolithus nicholsoni (Reed) Stetson, p. 88.

1940. Broeggerolithus nicholsoni (Reed) Whittington, p. 245.

1948. Broeggerolithus nicholsoni (Reed) : Bancroft in Lamont, p. 416.

I959& Broeggerolithus nicholsoni (Reed) : Dean, pp. 212, 214, 220.

1960. Broeggerolithus sp. (? nov.) Dean, p. 119, pi. 17, fig. 12.

1960. Broeggerolithus simplex Dean, p. 120, pi. 17, fig. 14.

DESCRIPTION. The cephalon is sub-semicircular in outline, broader than long, the maximum breadth of the syntypes ranging from 14 mm. to about 22 mm. The glabella is of moderate breadth, equal to about two-thirds of the total length, and often carries a small, apical ocellus just forward of centre. A pair of small, basal, glabellar furrows with apodemes is located immediately in front of a second pair of apodemes situated at the distal ends of the occipital furrow. The glabella is separated from the convex cheek-lobes by moderately-deep, almost straight, axial furrows. The occipital ring is small, strongly convex transversely, produced backwards and upwards to form a broadly-based occipital spine. The cephalic fringe is moderately declined, both frontally and laterally, though this may not always be apparent owing to compression of the specimen within a shaly matrix. The upper surface of the fringe is generally smooth and there is no development of raised interradial ridges such as are found in some earlier species of Broeggerolithus, for example B. broeggeri (Bancroft). One or two specimens show suggestions of such ridges, but these are almost certainly due to crushing and are not of constant form. There are four concentric rows of fringe-pits in front of the glabella, where the breadth (sag.) of the fringe contracts slightly so as to accommodate the frontal lobe of the glabella. There is a strong radial arrangement of pits frontally, and this

8o THE TRILOBITES OF THE CARADOC SERIES

persists laterally. The concentric arrangement is also marked, and the variation and norm of the four outer rows of pits is as follows : E2 = 19-24 (22), Ex = 21-23 (21), Ix = 21-22 (22), I2 = 20-22 (21). Up to three pits of E2 may be missing at the genal angle, and in certain rare instances an occasional pit of E2 may be absent laterally or anterolaterally. There is a notable lack of auxiliary E2 pits such as are found laterally in certain related species of Broeggerolithus. There is little marked differentiation in the size of pits, but those of Ij and I2 are slightly larger than the others, especially towards the posterior margin of the fringe. E2 and Ej are sited close together, but Ex and Ix are separated by a smooth, narrow, concentric " band " corresponding in position with a conspicuous girder on the underside of the fringe. A similar band of equal breadth separates I1 and I2, marking the position of a second less well developed pseudo-girder. There are seven to nine, most commonly eight, pits along the posterior margin of the fringe. I3 usually comprises fourteen or fifteen small pits, and is developed from Rn or thereabouts. The posterior margins of the fringe run slightly backwards, delimiting small genal prolongations, towards the genal angles which are produced to form librigenal spines ; the latter curve gently outwards and backwards, and their length is at least equal to that of the cephalon.

One of the syntypes, A. 29607, retains only five thoracic segments of typical trinucleid form. The axis of each is narrow (tr.) and bears a pair of apodemes situated just above the axial furrows. On each pleura, a moderately-deep pleural furrow, situated just forwards of centre, runs obliquely backwards from the axial furrow to the pleural point. A complete topotype thorax (PI. 7, fig. 4) exhibits the customary complement of six thoracic segments.

The syntype pygidium, A. 29615 (PL 7, fig. 2), is preserved as an internal mould and few details can be seen. The axis has three clearly defined axial rings, and three or four more are less well defined. The pleural lobes have three, or perhaps four, segments, separated by faint pleural furrows and widening (exsag.) towards the lateral margins.

HORIZON AND LOCALITIES. All Reed's syntypes were described by him as having been collected solely from the Alston Road cutting near Melmerby, but the state of preservation of most of the specimens indicates that they came from what are known as the Lower Melmerby Beds, and the probable type-locality is believed to be that shown in the present paper as locality J (see Text-fig. 5). One syntype, Sedg. Mus. A. 29614, is preserved differently from the rest and the matrix suggests a probable origin in the Upper Longvillian strata such as are found at Alston Road, locality H. All the other localities, from A to G, along the Alston Road have yielded Broeggerolithus nicholsoni, but the specimens are, in general, smaller than the syn- types.

Although trinucleid trilobites are so abundant almost everywhere at the Alston Road outcrop, elsewhere in the Inlier they are almost unknown from strata of Longvillian age. An uncommon exception is locality E. 3 at Harthwaite Sike where rare fragments, referred to B. cf. nicholsoni (see PL i, figs, n, 14), occur with an assemblage indicating the Bancroftina typa Zone of the Lower Longvillian.

LECTOTYPE, here chosen. Sedg. Mus. A. 29613 (PL 7, figs. 6, 9).

THE TRILOBITES OF THE CARADOC SERIES 81

PARATYPES. Sedg. Mus. A. 29607 ; A. 29608 ; A. 29609 (PI. 7, figs, i, 7) ; A. 29610 (PI. 7, fig. 10) ; A. 29611 (PI. 7, fig. 5) ; A. 29612 (PI. 7, fig. 8) ; A. 29614 (PI. 7, fig. ii) ; A. 29615 (PL 7, fig. 2).

DISCUSSION. In a recent account of trinucleid trilobites in south Shropshire (Dean, 1960 : 103) the species assigned to the genus Broeggerolithus were divided into three groups on the basis of small but significant differences in the structure of the cephalic fringe. B. longiceps (Bancroft) and B. transiens (Bancroft) were placed together in Group 3, whilst B. simplex Dean was placed doubtfully in Group 2. The last-named species is here regarded as a synonym of B. nicholsoni and may also be placed in Group 3. B. simplex was founded on a small cranidium from the Lower Longvillian of the Onny Valley and was at that time believed to be distinct. The pit count, however, falls within the limits of variation now established for B. nicholsoni, and additional material from Shropshire tends to confirm the identity of the two species

The fringe of Broeggerolithus transiens closely resembles that of the Melmerby species but its pit-count for the four outermost rows is noticeably smaller, and there are a few auxiliary pits situated anterolaterally in E2. Broeggerolithus longiceps is remarkably similar to B. nicholsoni. The former species is, unfortunately, known from only a comparatively small population sample in south Shropshire, but as far as can be ascertained the pit-count falls within the limits of that for B. nicholsoni. Like B. transiens, however, B. longiceps generally possesses a few auxiliary pits in E2, though situated posterolaterally, and these have not been found in B. nicholsoni. It is not known whether this is an invariable characteristic of B. longiceps, but if this should not prove to be the case then there is no other valid reason for regarding the species as distinct from B. nicholsoni. Certain well-preserved Shropshire speci- mens of B. longiceps have reticulate cheek-lobes, a feature not seen on any of the syntypes of B. nicholsoni but found on several specimens of the latter species from the Upper Melmerby Beds of the Alston Road cutting.

Outside the Cross Fell Inlier Broeggerolithus nicholsoni probably occurs at several localities in North Wales, associated with faunas of Longvillian age.

Broeggerolithus melmerbiensis sp. nov. (PI. 6, figs. 10, 13)

1959a- Broeggerolithus aff. nicholsoni (Reed) pars, Dean, p. 214.

DIAGNOSIS. Large Broeggerolithus generally similar to B. nicholsoni but with large number of fringe-pits, about one hundred, in four outermost concentric rows. Both Ex and E2 extend to the genal angles.

DESCRIPTION. One well-preserved specimen collected from the Alston Road cutting appears to resemble Broeggerolithus nicholsoni in most respects, but possesses a number of fringe-pits much larger than the norm for that species. The specimen has a closely similar radial and concentric arrangement of pits, but particularly noticeable is the manner in which rows E2 and Ex are placed close together, whilst rows E! and Ix are separated from each other by a wide, concentric " band " which

GEOL. 7, 3. 4

82 THE TRILOBITES OF THE CARADOC SERIES

coincides with the girder on the underside of the fringe. Ix and I2 are similarly separated from each other, and the pits composing these two rows become larger in size towards the posterior margin of the fringe. A conspicuous feature is the way in which both Ex and E2 are developed as far as the genal angles. Both I3 and I4 consist essentially of pits which are comparatively small, though increasing slightly in size posteriorly, and the two rows are developed respectively from Ri3 and Rig. The pit count for the specimen is as follows : £2 = 24 pits, Ei = 25 pits, Ii = 26 pits, 12 = about 25 pits. There are four continuous concentric rows of pits in front of the glabella, and seven pits are situated along each posterior margin of the fringe. The total number of pits in rows E2 to 12 inclusive is about one hundred, compared with an average of about eighty-five in Broeggerolithus nicholsoni (s. s.). The single available cranidium possesses four attached thoracic segments of typical Broeggerolithus aspect, but the total number originally present is unknown, as is the pygidium.

HORIZON AND LOCALITY. The holotype was collected from a loose nodule of impure limestone immediately below locality A in the Alston Road cutting, three- quarters of a mile north-east of Melmerby (see Text-fig. 5). It is almost certain that the specimen did, in fact, derive from this locality. The horizon is in the Long- villian Stage, and the strata at this point are believed to be the Upper Melmerby Beds, of Upper Longvillian age (Dean, 1959*1 : 213). The associated fauna includes Broeggerolithus nicholsoni, Brongniartella and FlexicaLymene.

HOLOTYPE. BM. In. 52558.

DISCUSSION. Although bearing a general resemblance to certain other species of Broeggerolithus such as B. nicholsoni, B. longiceps and B. transiens, the new form is unlikely to be confused with them on account of its much higher pit-count for the four outer rows, whilst no other species exhibits a comparable development of E2 to the genal angles.

Broeggerolithus cf. transiens (Bancroft) (PI. 8, figs, i, 3, 4, 6, 8, ii)

1929. Cryptolithus transiens Bancroft, p. 90, pi. 2, fig. 5. i959«. Broeggerolithus transiens (Bancroft) Dean, pp. 196-8, 207.

1960. Broeggerolithus transiens (Bancroft) : Dean, p. 123, pi. 18, figs. 2, 3, 7, 8, ii, 14. This reference contains a list of all other synonyms.

Numerous cephala and cranidia have been found, agreeing in all essentials with the description of the species from the type-area of south Shropshire (Dean, 1960 : 123). The pit count for the various rows of the cephalic fringe falls within the limits of variation of the Shropshire specimens, but instead of having one or two pits of Ej marginal at the genal angle, the Cross Fell specimens commonly have three pits so situated, though the number has been found to vary from one to four. Generally there are up to two auxiliary pits in the outermost concentric row, E2, of the Shrop- shire specimens, and these may sometimes be absent from the Cross Fell examples. This casts some doubt on the validity of such a feature as a means of separating closely-related species, but too few complete cranidia are available from either

THE TRILOBITES OF THE CARADOC SERIES 83

Shropshire or Cross Fell to give reliable statistics for the variation in E2. An analogous situation has already been noted with regard to Broeggerolithus nicholsoni and B. longiceps. The species is more abundant in the mudstones of the Cross Fell Inlier than in the corresponding coarser sediments of south Shropshire, and individuals frequently attain a larger size, the largest-known cephalon having a breadth of about 25 mm.

HORIZON AND LOCALITIES. In the Knock-Dufton district Broeggerolithus cf. tran- sient is fairly common in Dufton Shales of the Marshbrookian Stage at Swindale Beck. There it occurs in small numbers in strata thought to belong to the middle portion of the stage (locality B 12), but becomes more abundant in higher strata (localities B. n, 14, 16) which contain Kjerulfina cf. polycyma Bancroft and are considered to be equivalent to the Onniella reuschi Zone of south Shropshire. B. cf. transiens occurs also in Harthwaite Sike, east-south-east of Dufton (see Text-fig. 4) at localities E. 7, 8, 9?, 10-12, but the fauna there is sparse, composed in the main of smaller individuals.

Broeggerolithus sp. (PI. 8, %. 2)

19590. Broeggerolithus sp. (pars.) Dean, p. 207.

Among the numerous trinucleid trilobites found in the Marshbrookian rocks of Swindale Beck is one individual quite different from all the rest. The specimen comprises a fragmentary cranidium preserved as a limonitic external mould in a dark-grey, cleaved mudstone. The estimated length and breadth of the original cephalon are respectively 12 mm. (approx.) and 26 mm. Its most distinctive feature is the manner in which the two outermost concentric rows of pits, E2 and Ex, end abruptly without extending to, or even near, the genal angle as is customary in normal forms of Broeggerolithus. E2 extends only to the anterolateral angle, leaving three pits of Ex external to the margin. Ex stops far short of the genal angle, leaving five pits of Ix external to the margin, though separated from it by a smooth band which is equal in breadth to one row of pits. Such an arrangement results in the somewhat unusual, indented form of the cephalic margin in front of the genal angle, and the obliquely truncated shape of the anterolateral angle. The estimated number of pits originally present is as follows : E2 + e2 = 12, Ex + et = 15, Ix + ix = 19, I2 -f i2 = 19, I3 -f i3 = 10. There is a small triangular group of eight pits situated between I2 and I3 near the posterior margin of the fringe, and seven pits are aligned parallel to the latter. The pits of Ex and 1^ are of roughly equal size, larger than those of E2 and I3. The last four pits of I2 nearest the posterior margin are of particularly large size.

HORIZON AND LOCALITY. Found in mudstones of the Dufton Shales which contain Broeggerolithus cf. transiens (Bancroft) and Kjerulfina cf. polycyma (Bancroft), and belong to the topmost part of the Marshbrookian Stage, at locality B. 16 in Swindale Beck.

DISCUSSION. It is not unusual for specimens of Broeggerolithus to have a de- ficiency in the number of E2 pits near the genal angle, and in such forms as B.

84 THE TRILOBITES OF THE CARADOC SERIES

soudleyensis (Bancroft) and B. globiceps (Bancroft) some E2 pits may be absent frontally, but no known species compares in any way with the excessive loss of pits in the specimen now figured. In view of the large number of specimens of normal Broeggerolithus cf . tmnsiens associated with the cranidium it seems likely that the specimen represents a rare mutation or pathological form. Consequently it is not proposed to erect a new specific name, at least until further material is available.

Genus ONNIA Bancroft, 1933

TYPE SPECIES. Cryptolithus superbus Bancroft, 1929 by original designation of Bancroft (1933 : 2).

Onnia gracilis (Bancroft) (PI. 8, figs. 12, 13)

1929. Cryptolithus gracilis Bancroft, p. 94, pi. 2, figs. 8, 9. JQSQtf- Onnia gracilis (Bancroft) Dean, p. 207.

1960. Onnia gracilis (Bancroft) : Dean, p. 130, pi. 19, figs. 2, 7. This reference contains a

comprehensive synonymy of the species.

This species has recently been redescribed in detail by the writer (Dean, 1960 : 130) who gave the following figures for the range in variation of the number of pits present in the outermost four rows of the fringe. E2 + e2 = 31-37 (34), £!+€! = 21-25 (22), Ij + ij = 21-25 (23), I2 + ia = 21-25 (23) The figure in brackets represents the mode. Insufficient well-preserved material is available from the Cross Fell Inlier to give authentic figures for the corresponding variation, but the available material has yielded the following results: E2 + e2 = 32-37, Ej -f- ^ = 20-23, Ix + it = 20-22, I2 + i2 = 21-22. It is therefore apparent that the speci- mens fall within, or are very close to, the permissible variation for the species in its type-area.

HORIZON AND LOCALITIES. As in south Shropshire Onnia gracilis characterizes the middle portion of the Onnian Stage. It has been found in some abundance in black mudstones of the Dufton Shales at Pus Gill, localities A. 8, 9, u, 12, 13, 14 and 15. Again, as in Shropshire, the species is accompanied by a fauna which includes Onnicalymene onniensis (Shirley), Lonchodomas pennatus (La Touche), Chonetoidea sp. and Onniella broeggeri Bancroft.

Onnia superba (Bancroft) pusgillensis Dean

(PL 8, figs. 5, 7, 9, 10)

1961. Onnia superba pusgillensis Dean, p. 120, pi. 7, figs. 1-6. Includes full synonymy.

Onnia superba (Bancroft), the zone fossil of the topmost subdivision of the Onnian Stage in south Shropshire, has not been found in the Cross Fell Inlier, but is thought to be represented by a distinct, and possibly local, subspecies 0. superba pusgil- lensis. Although resembling 0. superba in almost all respects the Cross Fell form may easily be distinguished by the continuous development of I2 in front of the

THE TRILOBITES OF THE CARADOC SERIES 85

glabella, and by the greater development of I3 and I4, respectively from R$ or R4, and Ry.

HOLOTYPE. BM. In. 55707.

PARATYPES. BM. In. 50005 (PL 8, fig. 9) ; In. 50008 (PI. 8, fig. 5) ; In. 50049 ; In. 55704 ; In. 55705 ; In. 55706 ; In. 55708.

HORIZON AND LOCALITIES. Dufton Shales, Onnian Stage, Onnia superba Zone, Pus Gill, localities A. 5 and A. 16.

Subfamily TRETASPIDINAE Whittington, 1941 Genus TRETASPIS M'Coy, 1849

TYPE SPECIES. Asaphus seticornis Hisinger, 1840 by subsequent designation of Bassler (1915 : 1285).

Tretaspis cf. ceriodes (Angelin) donsi Stermer (PL 10, figs. 4, 6, 8)

1945. Tretaspis ceriodes (Angelin) var. donsi Stormer, p. 405, pi. i, fig. 8.

!959<*- Tretaspis cf. ceriodes (Angelin) : Dean, p. 207.

1961. Tretaspis cf. ceriodes donsi St0rmer : Dean, p. 129, pi. 9, figs. 7-9.

In southern Norway, Tretaspis ceriodes donsi has been shown by Stermer (1945 : 404) to be restricted to the upper part of the Upper Chasmops Limestone, 4b#. The earliest-known occurrence of Tretaspis in the Cross Fell Inlier is at Pus Gill, locality A. 13, in Dufton Shales belonging to the Onnia gracilis Zone of the Onnian Stage, and the evidence at this point, though fragmentary, suggests a comparison with the Norwegian subspecies. Additional, better-preserved material from the Onnia superba Zone at Pus Gill, locality A. 5, is too incomplete for detailed comparison, but shows all the principal features of T. ceriodes donsi. The horizon of the Cross Fell specimens corresponds fairly closely with that of the Norwegian material.

Tretaspis convergens Dean (PL 10, figs, i, 3, 5)

1961. Tretaspis convergens Dean, p. 127, pi. 9, figs. 1-6.

A detailed description of this species has already been given (Dean, 1961 : 127) to which nothing need be added here. T. convergens is a distinctive form, its closest relationships being with the species-group typified by Tretaspis seticornis (Hisinger), particularly T. seticornis var. anderssoni Stermer (1945 : 402, pi. i, fig. 2). T. convergens has so far been found at only one locality in the Cross Fell Inlier, namely B. 25 in Swindale Beck. There it occurs in the highest part of the Dufton Shales, belonging to the Pusgillian Stage, so that it is generally contemporaneous with Tretaspis seticornis anderssoni and allied forms as found in Etage 4ca of southern Norway.

HOLOTYPE. BM. In. 50059^, b (PL 10, figs, i, 3, 5).

Paratypes. In. 50030 ; In. 50037 (PL 10, fig. 2) ; In. 500580, b.

86 THE TRILOBITES OF THE CARADOC SERIES

Tretaspis kiaeri St0rmer radialis Lament (PL 9, figs. 2-4)

1941. Tretaspis kjaeri mut. radialis Lament, 1941, p. 456, figs. 5, 6.

1961. Tretaspis kiaeri radialis Lament : Dean, p. 122, pi. 7, figs. 7-9, pi. 8, figs, i, 3-5. Includes full synonymy of the subspecies.

The majority of the abundant specimens of Tretaspis collected from the Dufton Shales of the Cross Fell Inlier can be referred to this subspecies. T. kiaeri radialis was founded originally on two fragmentary specimens from the Portrane Limestone of Eire, but the description has since been supplemented, using material from the Dufton Shales (Dean, loc. cit.}, and the affinities with other species discussed.

HORIZON AND LOCALITIES. All the known specimens are from Dufton Shales belonging to the Pusgillian Stage. The exact distribution within the Pusgillian is not clear, owing to the predominance of successions affected by strike-faulting, but the subspecies appears to occur throughout most of the stage. Localities include the following : Pus Gill, A. 6, A. 18, A. 21, A. 24 to A. 30 ; Swindale Beck, B. 18, B. 22 to B. 26, B. 28, B. 33, B. 34 ; Dufton Town Sike, C. I to C. 6 ; Billy's Beck, D. i ; also the section at Hurning Lane, one mile north of Dufton.

Tretaspis kiaeri St0rmer duftonensis Dean

(PL 9, figs, i, 5-7)

1961. Tretaspis kiaeri duftonensis Dean, p. 125, pi. 8, figs. 2, 6-8.

The subspecies was described from a single, well-preserved specimen collected from Dufton Shales belonging to the Pusgillian Stage at Pus Gill, locality A. 27. Its closest relationship would appear to be with T. kiaeri radialis, from which it differs in having a conspicuously larger pit-count for Ej.2, a less well-developed concentric arrangement of I2_4 posterolaterally, as well as a larger, triangular area of irregularly arranged pits on the genal prolongations of the fringe. T. kiaeri duftonensis is not known with certainty outside the type-locality, though fragments of fringe suggest that it may occur elsewhere at Pus Gill, but identification is difficult in the absence of better-preserved material.

HOLOTYPE. BM. In. 5oo2oa, b.

Family CHEIRURIDAE Salter, 1864

Subfamily CYRTOMETOPINAE Opik, 1937

Genus PSEUDOSPHAEREXOCHUS Schmidt, 1881

TYPE SPECIES. Sphaerexochus hemicranium Kutorga, 1854 by subsequent designation of Reed (18960 : 119).

THE TRILOBITES OF THE CARADOC SERIES 87

Pseudosphaerexochus cf. octolobatus (M'Coy) (PI. 10, figs. 7, 9-12)

?i8gi. Youngia trispinosa Nicholson & Etheridge : Nicholson & Marr, p. 511. I959« Pseudosphaerexochus sp. nov., Dean, pp. 204, 208.

DESCRIPTION. The cephalon is known only from the cranidium. The glabella is strongly convex both longitudinally and transversely, subovate in plan, its maxi- mum breadth about, or slightly greater than, three-quarters of the sagittal length. It is bounded by deep, evenly-curved axial furrows, strongly convex abaxially, with deep, hypostomal pits. The frontal lobe is small, rather less than one-quarter of the glabellar length, and there are three pairs of equispaced glabellar furrows. The first and second pairs are parallel, extending inwards about one-quarter of the glabellar breadth ; they intersect the axial furrows at right-angles, but curve thence adaxially backwards, at the same time becoming rapidly shallower. The first and second pairs of glabellar lobes are identical in size and form, their convexity in line with the remainder of the glabella. The third glabellar furrows are deeper than, and parallel to, the first and second pairs, but curve backwards without reaching the occipital furrow and become shallower proximally. The occipital ring is small, narrow (tr.), strongly convex transversely, separated from the glabella by a moder- ately deep occipital furrow. The fixigenae are small, convex, and steeply declined abaxially. The pleuroccipital segment becomes slightly longer (exsag.) laterally, ending posterolaterally in a pair of short, broad, blunt fixigenal spines set a short distance inwards from the lateral margins. The pleuroccipital furrow is transversely straight for the most part, becoming shallower distally where it curves forwards towards, though without reaching, the lateral margins. The eyes have not been found preserved. The palpebral lobes are narrow, moderately convex abaxially, strongly arched longitudinally, and slightly divergent backwards ; they are defined proximally by palpebral furrows of moderate depth which die out quickly to both front and back. The anterior branches of the facial suture extend forwards from the eyes, parallel to the axial furrows, to cut the anterior border, whilst the posterior branches curve backwards distally to intersect the lateral margins just in front of the line of the pleuroccipital furrow. The librigenae have not been found. The surface of the glabella is covered with fine, evenly distributed granules, whilst all the furrows are smooth. The surface of the fixigenae is covered with large, dispersed pits, the intervening spaces, together with the surface of the pleuroc- cipital segment, being covered with smaller punctae which are apparent only on the external mould. The internal mould of the glabella is ornamented with closely- grouped, small, prickly granules, probably representing the infillings of canals in the original test.

The hypostoma and thorax are not known.

An incomplete pygidium, which must have been more than twice as broad as long, is the only specimen that has been found (PI. 10, fig. 7). It is made up of four segments which are produced backwards to form four pairs of strong, tapering spines ; the latter are separated from one another by well-defined notches, and their tips are stepped backwards slightly en echelon from first to fourth. Only three

88 THE TRILOBITES OF THE CARADOC SERIES

axial segments are visible, the first two well defined by deep ring furrows, and the third poorly defined by two shallow transverse notches near the bases of the fourth pair of pleural spines. The axial furrows comprise broad, shallow grooves, moderately convergent backwards. Excluding the furrows, the surface of the pygidium is granulate on the internal mould, but finely pitted on the external mould.

HORIZON AND LOCALITIES. The earliest-known occurrence of the species in the Cross Fell Inlier is in the Dufton Shales, Onnian Stage, Onnia superba Zone of Pus Gill, locality A. 5. Most of the available specimens are, however, from Dufton Shales belonging to the Pusgillian Stage at Swindale Beck, locality B. 25. Other localities, all in Pusgillian strata, are at Pus Gill, localities A. 6 and A. 30, and at Dufton Town Sike, locality C. 6, east of Dufton.

DISCUSSION. The specific name Pseudosphaerexochus octolobatus has been used to cover forms of the genus occurring in British Ordovician strata of various ages. The holotype, described and figured by M'Coy (1849 : 4°7 » *» Sedgwick & M'Coy, 1851, pi. IG, fig. 10) as Ceraurus octolobatus, is a pygidium, Sedg. Mus. A. 11606, from the Rhiwlas Limestone, of Ashgill age, near Bala, and the species must be redescribed in detail before satisfactory comparisons can be made. Specimens from the Ashgill Series, Drummuck Group, of Girvan were assigned by Reed (1906 : 141, pi. 18, figs. 8-n) to Cheimrus (Cyrtometopus] octolobatus, and these appear to be identical with the Cross Fell specimens, at least as far as the cephalon is concerned.

Pseudosphaerexochus has been recorded from the Onnian Stage of the Onny Valley in south Shropshire (Dean, 19610 : 316), but the material there is too fragmentary for comparison with that from Cross Fell.

Family ENCRINURIDAE Angelin, 1854 Subfamily ENCRINURINAE Angelin, 1854

Genus ENCRINURUS Emmrich, 1844

TYPE SPECIES. Entomostracites punctatus Wahlenberg, 1821 by original designa- tion of Emmrich (1844 : 16).

Encrinurus sp.

(PI. n, figs, i, 4) 19590. Encrimtrus sp., Dean, p. 214.

Only one specimen has been collected, a pygidium about 5 mm. long and 4-5 mm. broad frontally, preserved as an internal mould with part of the corresponding external mould. Frontally the axis occupies about one-quarter of the maximum breadth ; it is delimited by deep, smooth axial furrows and tapers backwards to a narrow tip. There are eight pairs of pleural ribs which terminate laterally in small free points ; the pleurae of the eighth pair almost coalesce with the terminal piece of the axis, from which they are separated by a pair of shallow grooves. The axis as far as the eighth pair of pleurae carries fifteen axial rings, but beyond this position is apparently smooth. The ring furrows, apart from the first three or four, become

THE TRILOBITES OF THE CARADOC SERIES 89

shallower medially and there are traces of small median nodes on the third, fifth and eighth axial rings. The remainder of the dorsal surface is smooth.

HORIZON AND LOCALITY. Locality H (see Text-fig. 5) beside the Alston Road, three-quarters of a mile north-east of Melmerby. The strata, the Upper Melmerby Beds, contain fossils indicating the lower part of the Upper LongvilHan Substage, the equivalent of the Kjaerina bipartita Zone or Alternata Limestone in south Shropshire.

DISCUSSION. Few Caradoc species of Encrinurus are available for comparison. Encrinurus sp. (? nov.) from the Marshbrookian Stage of Shropshire (Dean, 1961^, pi. 49, figs. 10, 12) has a similar number of ribs but a larger number of axial rings, at least seventeen. The Alston Road specimen may well prove to represent a new species.

Subfamily DINDYMENINAE Pfibyl, 1953 Genus DINDYMENE Hawle & Corda, 1847

TYPE SPECIES. Dindymene fridericiaugusti Hawle & Corde, 1847 by subsequent designation of Barrande (1852 : 816).

Dindymene duftonensis sp. nov. (PL n, fig. 13)

19591*. Dindymene sp. nov., Dean, pp. 198, 207.

The holotype is an incomplete cranidium of estimated breadth 4 to 5 mm., ex- cluding fixigenal spines, the maximum breadth being roughly twice the length. The glabella is strongly convex, both longitudinally and transversely, narrow posteriorly but expanding forwards until equal to rather more than one-third of the cephalic breadth. The axial furrows are deep and narrow posteriorly, but widen forwards where they curve distally to join the lateral border furrow which skirts the plump fixigenae. The occipital furrow is shallow and broad (sag.) medially, deepen- ing laterally where a pair of deep apodemal pits is situated ; the occipital ring is small, curving forwards abaxially to form a pair of occipital lobes. The pleuroc- cipital segment is uniformly narrow (exsag.), transversely straight, separated from the fixigenae by a parallel, moderately-deep, pleuroccipital furrow. The external mould shows that the narrow (tr.) lateral borders meet the pleuroccipital segment at the genal angles which are produced to form a pair of fixigenal spines, long, slender, slightly curved, convex side forwards, and broadly splayed backwards. The surface of the fixigenal spines, lateral border and pleuroccipital segment is uniformly and finely granulate, appearing almost smooth. The surface of each fixigena is covered with fine wrinkles, which contain numerous small pits, and carries seven large tubercles ; three of the latter are situated anterolaterally in a row parallel to the lateral border furrow, one is situated medially just in front of the pleuroccipital furrow, and the remainder are arranged more or less sporadically over the fixigena. The surface of the glabella, though incomplete, is estimated to have carried about twenty tubercles of moderate size. Three of these form a median, longitudinal row

9o THE TRILOBITES OF THE CARADOC SERIES

extending half-way from the occipital furrow to the front of the glabella and are flanked by two pairs of tubercles situated a short distance adaxially from the axial furrows. The remaining tubercles are grouped more closely together across the frontal lobe, and the intermediate spaces are finely granulate. These figures apply to the partially preserved holotype, and the material available is insufficient to decide whether there is any variation in the disposition of the tubercles.

The remainder of the exoskeleton is unknown.

HORIZON AND LOCALITY. Dufton Shales belonging to the Marshbrookian Stage, probably the middle or upper third, at locality E. 12 (see Text-fig. 4) in Harthwaite Sike, east-south-east of Dufton.

HOLOTYPE. BM. In. 546520, b, the latter, an external mould, being figured here in the form of a latex cast.

DISCUSSION. The known species of Dindymene were reviewed recently by Kielan (1959 : 146 et seq.). Of them, the species with which D. duftonensis may best be grouped are D. ornate, Linnarsson, of Ashgill age, and D. plasi (Kielan, 1959 : 151, pi. 29, figs. 1-3) from the Llanvirn Series of Bohemia. Like them it is equipped with genal spines directed posterolaterally, but those of the Cross Fell species are notably longer. Both the extra-British species differ from D. duftonensis in having a particu- larly large tubercle, almost a cephalic spine, sited medially, one-third of the distance from the occipital furrow to the front of the glabella ; in this respect they somewhat resemble the more extreme development of a cephalic spine seen in the recently described Cornovica, from the Lower Llanvirn of west Shropshire (Whittard, 1960 : 122), a genus which possesses, however, glabellar furrows and eleven thoracic seg- ments. The fixigenae of D. duftonensis carry a similar number of large tubercles to those of D. plasi and D. ornata : the glabella, however, has a greater number of tubercles than that of D, ornata but fewer than that of D. plasi. As with D. ornata the space between the glabellar tubercles is finely granulate, a feature apparently not found in D. plasi.

Harper's (1956 : 389) record of Dindymene cf . ornata from Upper Longvillian strata at Llanystwmdwy, Carnarvonshire, suggests that D. duftonensis may possibly be represented in the North Welsh faunas.

Dindymene sp.

(PL n, fig. 6)

i959<z. Dindymene sp., Dean, pp. 194, 207.

Two fragmentary cranidia, one of which is figured here, have been collected from the Upper Longvillian of Swindale Beck. In size and general form they match the type material of D. duftonensis but, as the dorsal surface is not preserved, precise identification has not been possible, though there are faint traces of some large tubercles. The more complete specimen has a narrow (sag.), upturned, anterior border, apparently separated from the glabella by a narrow (sag.), anterior border furrow containing the facial suture. The latter follows the outline of the frontal lobe as far as the axial furrow, beyond which it runs parallel to the margin of the cephalon and separates a narrow (tr.), smooth border from the fixigena. It has not

THE TRILOBITES OF THE CARADOC SERIES 91

been possible to trace the line of the suture beyond the anterolateral portion of the glabella.

HORIZON AND LOCALITY. Dufton Shales containing Kjaerina geniculata Bancroft and forming the upper part, the Kjaerina typa Zone, of the Upper Longvillian Substage, at locality B. 5 in Swindale Beck.

Subfamily CYBELINAE Holliday, 1942 Genus ATRACTOPYGE Hawle & Corda, 1847

TYPE SPECIES Calymene verrucosa Dalman, 1826 by original designation of Hawle & Corda (1847 : 9°)-

Atractopyge scabra sp. nov.

(PI. II, figs. 2, 3, 10)

1891. Cybele verrucosa Dalman : Nicholson & Marr, pp. 505, 511. I959a- Atractopyge aff. aspera (Linnarsson) : Dean, p. 207.

DIAGNOSIS. Glabella clavate, slightly broader than long, with frontal lobe strongly convex forwards. Three pairs equisized glabellar lobes. Eye-ridges run from palpebral lobes towards first glabellar furrows. Surface of test, excluding furrows, covered with coarse tubercles, some of conspicuously large size. Pygidium longer than broad. Four pairs of ribs ending in free points arranged en echelon. Narrow axis with four continuous axial rings and a further fifteen or sixteen incomplete rings.

DESCRIPTION. The length of the cranidium is rather more than half the breadth. The glabella is moderately convex, clavate in outline, and attains its maximum breadth, slightly greater than the median length, across the lateral extremities of the anterior border. There are three pairs of glabellar furrows, represented by deep, almost slot-like pits situated a short distance adaxially from the axial furrows. The first pair of glabellar furrows is situated about mid-way between the frontal margin and the occipital furrow, the second and third pairs being then positioned at regular intervals so as to give three pairs of almost equisized glabellar lobes, their long axes strongly divergent forwards. The occipital ring is short (sag.), convex forwards medially ; laterally it curves forwards slightly to form a pair of occipital lobes, immediately in front of which a pair of apodemal pits is situated at the extremi- ties of the broad (sag.), smooth, moderately-deep occipital furrow. The axial furrows are deep, wide (tr.), smooth, and rounded basally in cross-section ; from the occipital ring they follow a slightly divergent course forwards as far as the first glabellar furrows, whence they diverge more sharply to the false preglabellar field. The frontal lobe of the glabella is strongly convex forwards where it is bounded by a broad (sag.), smooth furrow, well defined but not deep, which intersects the axial furrows opposite a pair of deep, hypostomal pits. Beyond this furrow the anterior border is only slightly raised, but it is rendered more conspicuous by the presence thereon of a row of well-developed tubercles of both large and medium size. Orna- mentation of similar type, but including a greater number of large tubercles, covers

92 THE TRILOBITES OF THE CARADOC SERIES

the surface of the remainder of the glabella with the exception of the glabellar lobes. In some individuals two, or even four, of the largest tubercles on the anterior border may be arranged symmetrically about the sagittal line, and two or three pairs of those on the main body of the glabella have been found to behave similarly, but it has not proved possible to utilize satisfactorily, with the available material, the notation proposed by Tripp (1957) for the tuberculation of certain species of Encrinurus. The fixigenae are strongly convex, with faint suggestions of eye ridges running towards the first glabellar furrows, and are surmounted by prominent, pedunculate, palpebral lobes. No palpebral furrows have been seen on the latter, which have a finely granulate, almost smooth surface, contrasting with the coarse tuberculation of the fixigenae which ends abruptly at the base of the palpebral lobes. The pleuroccipital furrow is straight for about half its length (tr.) but then turns markedly backwards and finally dies out just before reaching the lateral margins. The pleuroccipital segment, which follows the course of the pleuroccipital furrow, is extremely narrow (exsag.) near the axial furrows but then widens appreciably to- wards the apparently rounded genal angles. Each half of the pleuroccipital segment carries about seven or eight tubercles arranged fairly regularly along its length (tr.).

The librigenae, hypostoma and thorax are not known.

Only a few isolated pygidia have been found, the largest of which is just over 12 mm. long. The best-preserved specimen (PI. n, fig. 10) is about 9-5 mm. in length, with a maximum breadth of 8 mm. It is subovate in plan and only moderately con- vex transversely. There are four pairs of pleural ribs, separated from each other by strong rib furrows which become less well developed from first to fourth. The ribs of the first pair curve abaxially backwards for about half the length of the pygidium and then, more gradually, adaxially. The remaining ribs are subparallel to the first pair but become successively less strongly curved until those of the fourth pair are almost straight, converging backwards subparallel to the axial furrows. The ribs terminate in small, free points which are " stepped " backwards en echelon from first to fourth. The axis is in the form of an acute isosceles triangle, the two long sides of which meet posteriorly at about 20 degrees, and there may be up to nineteen, or perhaps twenty, axial rings visible. The first four axial rings are well defined, continuous with the corresponding pairs of ribs. Frontally the axial furrows are present merely as shallow grooves, but they become sharply defined behind the fourth axial ring. Sometimes a fifth axial ring may be defined by a transversely continuous ring furrow, but usually the greater part of the axis bears a smooth median band, occupying about one-third of its breadth, on either side of which the axial rings are clearly defined. There is a small, pointed terminal piece, behind which the points of the fourth pair of ribs extend a little way. The greater part of the surface of the pygidium is smooth but there are traces of incipient tubercles on occasional axial rings, whilst up to five larger tubercles may be found along each rib, particularly its hindmost two-thirds.

HORIZONS AND LOCALITIES.