August 22, 1901] 



NA TURE 



401 



BATRACHIANS ANU REPTILES IN THE 

 CAMBRIDGE NATURAL HISTORY} 



IN the preface to this welcome volume the author 

 reminds his readers of the words of Linnaus, 

 " Amphibiologi omnium paucissimi sunt nullique veri.' 

 What progress has been accomplished by the " Amphi- 

 biologi" — herpetologists we now term them — in dealing 

 with the "pessima tetraque animalia" during the 150 

 years which have elapsed since this statement of the 

 great naturalist ,^annot be better realised than by a 

 perusal of the excellent contribution supplied by Dr. 

 Gadow for the eighth volume of the "Cambridge 

 Natural History." 



This work is not only of the highest interest in bring- 

 ing together in a small compass and in a charming style 

 the essence of a most voluminous literature ; it derives 

 special value from the authority of its writer as an 

 anatomist and observer of the Batrachians and Reptiles 

 both in their native haunts and in the vivarium. 



Not content with giving us the benefit of his wide e.\- 

 perience in the departments to which he has devoted so 

 much study, Dr. Gadow has also suggested various 

 reforms in the general classification, thus raising the 

 work far above the usual standard of this kind of 

 semi-popular treatises. 



The following table will show the classification 

 adopted, and which, on the whole, reflects so well the 

 state of our present knowledge. The author e.xplains in 

 the preface that the principal groups are called sub- 

 classes in order to emphasise their ta.\onomic import- 

 ance in comparison with the main groups of birds and 

 mammals : — 



/ Stegocephali 



' Lissamphibia 



I Proreplilia 

 Prosauria 



Theromorpha 



Crocodilia 



Plesiosanria 



Ichthyosauria 



Pterosauria 



Pythonomorpha 



Order 



t Lepospondyli 



I Temnospondyli 

 I Stereospondyli 

 / Apoda 

 ' Urodela 



I Anura 



( Microsauri 



I Prosauri 



f Pareiasauri 

 ) Theriodonlia 

 \ Anomodoniia 

 ' Placodontia 

 I Atheca 



( Thecophora 



I Sauropoda 

 I Theropoda 



( Orthopoda 



I Ceratopsia 

 Pseudosuchia 

 Parasuchia 

 Eusuchia 

 ( Nolhosauri 

 ( Plesiosaiiri 

 Ichthyosauri 



Pterosaur! 



( Dolichosauri 

 \ Mosasauri 



Suborder 



f Branchiosauri 

 y Aistopodes 



/ Aglossa 



\ Phaneroglossa 



( Protorosauri 

 [ Rhynchocephali 



, Cryptodira 

 Pleurodira 

 Trionychoidea 



\ Stegosauri 

 ( Ornithopodi 



( Pterodactyl! 

 1^ Pteranodonles 



Sauria 



.Amphibia 

 .tural History." 



I Geckones 

 Lacertre 

 Chamitleontes 



( Lacenilia 



I Ophidia 

 The boldest attempt at innovation in taxonomy 



Reptiles. 

 Vol. viii. 

 1 and Co., Ltd.) Pri< 



NO. 1660, VOL. 64] 



By Hans Gadow 

 Pp. Jtiii -I- 668 ; 181 



consists in the removal from the class ISatrachia or 

 Amphibia, as generally understood, to that of Reptilia, 

 not only of the Microsauria, but of a number of other 

 members of Cope's Stegocephalia. But this change 

 is not one that is likely to commend itself. We all 

 know how, in the light of recent pakeontological dis- 

 covery, most of the supposed distinctive features of the 

 two classes in question have faded away, as instanced by 

 Prof. Seeley's proposal to unite the Stegocephalia with 

 the Reptiles, and Prof. Credner's establishment of the 

 group Eotetrapoda for the reception of the earlier 

 Batrachians and Reptiles. However, one thing appears 

 certain to me : the Stegocephalia, as defined by Cope, form 

 one compact group, distinguished from both Batrachians 

 proper and Reptiles by the presence of additional 

 dermal bones in the skull — the occipital (dermo-occipital) 

 and the so-called "epiotic," which 1 regard as the 

 homologue of the post-temporal of Fishes — and, further, 

 in all cases where the pectoral arch is known, by 

 their conforming to the type of the Crossopterygian 

 and early Ganoid Fishes in the possession of the 

 element termed cleithrum by Gegenbaur (clavicle of 

 ordinary Teleosts) in addition to the clavicle proper. 

 These highly important features, connecting the Crosso- 

 pterygians with the Stegocephalians, are relegated to the 

 background by Dr. Gadow, who prefers to establish the 

 turning-point where to part the Reptilian phylum from 

 the Batrachian upon the constitution of the elements of 

 the vertebral column, Batrachians being defined as 

 acenirous, pseiidocenlrous or no/ocen/rozis, that is to say, 

 in which the author's "dorsal arcualia" are reduced or 

 absent, Reptiles as <^asiroce>i/rous, the centra of the 

 j vertebrEe bemg formed by pairs of " interventralia," while 

 I the " basiventralia" (intercentra of Cope) are reduced, 

 persisting either as wedgebones or as intervertebral pads, 

 or absent. This is the application of the views set forth 

 by the author in his well-known paper published in the 

 Philosophical Tfansaclions for 1896; but it must be 

 admitted that, so far as the Stegocephalia are 

 concerned, the ideal distinction between inter- 

 dorsalia and interventralia cannot be practically 

 applied, owing to the types which connect Eryops, now 

 proposed to be placed with the Reptiles together with 

 the Embolomeri and Microsauria, and Arche^osaurus, 

 associated with the Labyrinthodonts. Whatever measure 

 of truth Dr. Gadow's theory of the evolution of the 

 vertebral column may contain, it is very doubtful svhether 

 any students of the fossil remains will be able to agree 

 with him in regarding the composition of the tripartite 

 vertebr.-E of these genera as due to " superficial resem- 

 blance." " -After all," the author adds (p. 285), "we feel 

 certain that Reptiles have arisen from Stegocephalous 

 Amphibia, and it is in the Lower Permian, exactly where 

 the debatable creatures lived side by side with the 

 Stegocephali, undoubtedly likewise temnospondylous, 

 that the change from Amphibia into Reptiles seems to 

 have taken place." 



It is highly probable that the Stegocephalians will be 

 found to have been derived from the Crossopterygians 

 and to lead, on the one hand, to the Batrachians through 

 the Branchipsauria, and, on the other hand, to the Reptiles 

 through the Tvlicrosauria. Perhaps the best means of 

 getting over the difficulty with which we are confronted 

 would be to raise the Stegocephalians to the rank of a 

 class, which is quite capable of exact definition. But 

 there is certainly no sufficient justification at present 

 for the proposal to unite Eryops and the Embolomeri 

 {Proreplilia of Gadow) with the Reptiles rather than 

 with the Batrachians. 



I would add that if Dr. Gadow thus repudiates the 

 classification of Cope, it is contrary to the rules of 

 nomenclature to make use in the sense he does of the 

 name Stegocephali. 



On the other hand, I hail with satisfaction the 



