VERTEBRATA. 283 



II. Mesosuchia : bony plates of the palatine bones prolonging the nasal 

 passages, and giving rise to secondary posterior nares ; vertebral 

 centra amphicoelian. Genera: Steneosaunis, Pelagosmrus, Teleosaurus, 

 J'eleidosauras^ Metriorhynchas^ Goniopholis, Macro rhynchus, Pholidosau- 

 rus, Hyposaurus. III. Eusuchia : both pterygoid and palatine bones 

 giving off plates which prolong the nasal passages ; vertebral centra 

 mostl}- procrjelous. Genera : 'Thoracosaurus, Holojys, and recent forms. 

 The Parasuchia are the least modified group, the Eusuchia the " most 

 Crocodilian of Crocodiles," and the Mesosuchia, while more nearly con- 

 nected with the latter than the former group, are intermediate. The 

 geological evidence establishes the appearance of these reptiles in the 

 order of their departure from the Laccrtilian and their approach to the 

 Crocodilian type. The Parasuchia are Triassic, the Mesosuchia post- 

 Triassic but pre-Cretaceous, the Eusuchia post- Cretaceous. 



A fragment of a crocodilian skull from the Wealden of the Isle of 

 AVight is described and figured. It approaches the Eusuchia more 

 than any other Mesosuchiau. The imperfection of the skull and the 

 absence of teeth prevent comparison with other AVealden Crocodiles. 



The Lacertilia and Ornithoscelida are examined to see whether 

 these types exhibit any evidence of a similar evolution to that of 

 the Crocodilia. The vertebral column of Lacertilia has undergone a 

 change corresponding to that which has occurred in the Crocodilia. 

 All Lacertiliaus jjrior to those of the Purbecks have amphicoDlous 

 centra, while most existing lizards are proccelous. This change 

 seems to have occurred earlier in the Lacertilia than in the Cro- 

 codiles, as a sacral vertebra of a lizard from the Purbecks has 

 the centrum concave in front and convex behind. With regard to 

 the Ornithoscelida, some confirmations and corrections of previous 

 statements are noted. The ilium of the Thecodontosauria had been 

 turned the WTong way. Instead of being more Ornithoscelidan 

 than Megalosauriis, it is really more Lacertilian. The Triassic Orni- 

 thoscelida are less ornithic and more lacertilian than those belonging to 

 the second half of the Mesozoic period. The oldest Crocodiles differ 

 less than the recent ones from the Lacertilia ; and as the oldest 

 Ornithoscelida also approach the Lacertilia, the two groups seem to 

 converge towards the common form of a Lizard with crocodilian 

 vertebrae. Cetiosaurus also has a vertebral system like that of the 

 Thecodontosauria and Crocodilia, but more Lacertian limbs ; Stenopelyx 

 may be in the same case. It may therefore be convenient to sepaiate 

 the Thecodontosauria, Cetiosaurus, and perhaps Stenopelyx, as a grou^) 

 " Sauroscelida," distinct from both Ornithoscelida and Crocodilia. 



L. C. M. 



Kapff, Dr. Ueber cinen neuen Fund von Sauiierresten im Stuben- 

 sandstein. [New Discovery of Saurian Remains, &c.] Vtrh. h.-h, 

 (jeol. Jieichs. pp. 303, 304. 



In the same Keuper quarr}' where Teratosarvs sutvictis was found, 

 further excavations have produced several skeletons of Lizards ; it is 



