AND ON THE EVOLUTION OF THE CKOCODILIA, 433 



nothing of the structure of the secondary posterior nares in either 

 Goniojpholis or Macrorhynchus. 



The results obtained from the investigation of the nature and 

 order of the successive changes which the Crocodilia have undergone 

 since their first appearance in the Triassic epoch, naturally suggest 

 the inquiry whether the nearest living and extinct allies of the 

 Crocodiles, the Lacertilia and the Ornithoscelida, which are traceable, 

 the former from the present day to the Permian epoch, the latter 

 from the later Cretaceous to the Triassic epoch, exhibit any evidence 

 of having been subjected to a similar process of evolution. 



In the case of the Lacertilia. it is unfortunate that nothing of 

 moment is known respecting the cranial structure of the Permian 

 forms. In the rest of the skeleton it is hard to find any important 

 deviation from the type of the existing Lizards except in the cha- 

 racters of the centra of the vertebrae, which are amphiccelous 

 instead of being, as in the majority of existing Lizards, proccelous. 

 In the Trias, the only Lacertilia at present known are Hypero- 

 dapedon, Bhynchosaurus, and Telerpeton ; and as I have shown on a 

 previous occasion *, the first singularly resembles the existing New- 

 Zealand Hatteria, the resemblance of which to Rhyncliosaurus had 

 already been indicated by Professor Owen and Dr. Giinther. 



In the Museum of Practical Geology, there is a sacral vertebra of 

 a Lizard from the Purbecks, with the anterior face of the centrum 

 concave and the posterior convex. All earlier Lacertilians at 

 present known have amphiccelous vertebral centra, while all but a 

 few existing Lizards are proccelous. 



Thus it would appear that, on the whole, the vertebral system of 

 the Lizards has undergone a change corresponding to that which 

 has occurred in the Crocodiles, and that this modification of the 

 articular faces of the vertebrae took place at an earlier period in the 

 Lizards than in the Crocodiles. Apart from this, there is no 

 evidence that the Lacertilian type of structure has undergone any 

 important change from the later Palaeozoic times to the present day. 



The discoveries of American palaeontologists prove that the 

 Omitlioscelida abounded in the latter part of the Cretaceous epoch, 

 up to the very verge of the commencement of the deposition of the 

 Tertiary rocks. 



In a paper on the " Classification of the Dinosauria, with observa- 

 tions on the Dinosauria of the Trias," read before the Society in 

 1869 f , I endeavoured to show that there was evidence of the 

 existence of varied forms of Dinosauria in the Trias, and I dis- 

 cussed, at some length, the case of Zanclodon (which is probably 

 identical with Teratosaurus of von Meyer), from the Upper Keuper 

 of "Wiirttemberg. 



In 1873 I had the opportunity of paying a short visit to Stuttgart ; 

 and with the courteous permission and aid of Prof. Praas, I examined 

 the fine series of remains of Zanclodon in the museum of that city. 



* " On Hyperodcfpedon^ Quart. Journ. Geol. Soc. vol. xxv. (1869) p. 138. 

 t Quart. Journ. Geol. Soc. vol. xxyi. (1870) p. 32. 



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