NATURE 



[May 2, 1889 



in this volume into the following groups of higher than 

 generic rank, viz. : — 



Order Rhynchocephalia. 



Fam. Hatteriidx. 



Order Chelonia. 



Sub-order I. AtheC/E. 



Fam. I. Sphargidas. 

 Sub-order 11. THEOCorHORA. 

 Super- fam. A. Cryptodira. 

 Fam, 2. Chelydridse. 



Order Emydosauria. 



Fam. Crocodilidne. 



There are a few points in regard to the nomenclature of 

 £0 ne of these groups where the author's views are at 

 least open to question. This is especially the case with 

 regard to the selection of the name Emydosauria to 

 replace the almost universally accepted Crocodilia. The 

 reason for the selection of ihis term appears to be, that 

 it is the earliest. In common, however, with a large 

 number of English zoologists, we (while deprecating 

 the needless introduction of new ordinal names) hold 

 that, although the enforcement of the rule of priority 

 is, unfortunately, in most cases, obligatory as regards 

 generic and specific names in order to avoid endless 

 confusion, yet no such rule is necessary in respect to 

 higher groups, where the name that has come to be gener- 

 ally used ought to be maintained. Then, again, the un- 

 grammatically formed name Athecns, for which Prof. E. 

 D. Cope is responsible, should clearly have been amended 

 to Athecata ; while, since the name Thecophora — or, more 

 correctly, Thecaphora — clashes with the same term em- 

 ployed for a group of Hydroid Zoophytes, we think the 

 author would have been better advised had he followed 

 his own article on Tortoises in the latest edition of the 

 " Encyclopaedia Britannica," and employed the term 

 Testudinata in this sense. Finally, since the generic 

 names Hatteria and Sphargis are rejected in place of 

 the earlier Sphe77odo7i and Dcnnochelys (which, by the 

 way, should clearly be amended to Dennaiochelys), we 

 cannot follow the author in retaining the names Haiteriida 

 and SphiV'gidcE for the families respectively represented 

 by these two genera. If a family name means anything 

 at all, it means a group of animals more or less nearly 

 allied to a certain genus selected as the type, and it is 

 therefore clearly illogical to call the Sphmodon-\\Vt 

 reptiles JlaHeriida: when no such genus, as Hatteria 

 exists. Further, to show t'.ie absurdity to which this ad- 

 herence to the rule of priority, in place of that of com- 

 mon-sense, in the case of family names might lead us, 

 we have only to suppose that the name Hatteria, in place 

 of being rejected as later than Sphenodon, had been re- 



jected on account of being preoccupied by another form 

 belonging to, but not the type of, a distinct family. In 

 such case, we should have the family name Hatteriida 

 for a group of animals which did not include the genus 

 Hatteria! On these grounds we hold that the names 

 Sphenodotitidce and Derinatochclydidce should certainly 

 replace Hatteriidce and Sphargidce. 



In regard to the Rhynchocephalia, the author considers 

 that its one existing representative indicates an extremely 

 generalized type of reptile, of which the relations appear 

 to be at least as close to the Chelonia as to the Lacer- 

 tilia. In this respect, Mr. Boulenger departs very widely 

 from the views of Prof. Huxley ; and although we think 

 he is undoubtedly justified in maintaining the Rhyncho- 

 cephalia as a distinct order, yet we cannot overlook the 

 circumstance that the Homaiosaurian lizards of the Litho- 

 graphic stone, which appear to be Rhynchocephalians, 

 are most probably closely related to the ancestors of the 

 Lacertilia. 



The whole of the existing Crocodilians are included in a 

 single family — against the three families adopted by Dr. 

 Gray. The true Crocodiles are divided into CrocodiluszxiA. 

 Osteolamus, according to the absence or presence of a 

 forward prolongation of the nasals to divide the anterior 

 nares ; while among the Alligators a similar feature 

 serves to distinguish Alligator axi^ Caiman. The Croco- 

 dilus po7idiceriantis of Gray is considered to be based 

 upon a young specimen of C. porosus. The Gharial skull 

 mentioned on p. 276 as having been obtained at Poonah 

 would appear to be incorrectly labelled, as this reptile is 

 unknown in Bombay. 



Taking a brief general survey of the Chelonia, we 

 think the author is fully justified in adopting Prof Cope's 

 division of the order into the two primary groups of 

 Atheca-' and Thecophora ; the great difference in the 

 structure of the skull, as exemplified by the absence of 

 descending parietal plates in the former, being a charac- 

 ter which is of itself apparently sufficient to uphold this 

 division. We are aware, indeed, that Dr. G. Baur, of 

 Newhaven, Conn., holds a precisely opposite view, and, 

 in place of regarding the Athcac as the most generalized 

 type of existing Chelonians, looks upon them as an ex- 

 tremely specialized branch derived from the Cryptodiran 

 Chelonidcc. There are, indeed, certain superficial, and 

 probably adaptive, resemblances between these two types 

 of marine turtles, but the fundamental differences are so 

 great as apparently to render Dr. Baur's views untenable. 

 And we should much like to ask that authority how he 

 would explain the appearance of transverse processes to 

 the dorsal vertebra of one of the extinct Athecit on his 

 own hypothesis of their phylogeny. 



The three " super-families " into which the Thecophora 

 are divided are, to a great extent, distinguished by the 

 mode of flexure of the neck, by cranial characters, and 

 by the relations of the pelvis to the shell. Certain very 

 peculiar features in relation to the mandibular articula- 

 tion, the tympanic ring, and the arrangement of the bones 

 of the palate serve to distinguish the existing Cryptodira 

 of the southern, from the Pleurodira of the northern hemi- 

 sphere ; but we have considerable doubts whether these 

 characters will be found to obtain in the Mesozoic repre- 

 sentatives of the group, and whether they are not rather 

 acquired than arcaaic features. We should, indeed, 



