212 



REPTILIA. 



important and the most widely distributed. Of these, Teleo- 

 saurus is a well-known IMesozoic type, represented by many 

 Jurassic species, and having the jaws greatly elongated, and 

 carrying numerous conical teeth, as in the living Gavials. 

 The dermal scutes are large and exceptionally strong and 

 solid. The Jurassic genus Steneosaurus (fig. 562) also com- 

 prises Jurassic Crocodilians, which, 

 except for their amphicoelous ver- 

 tebra?, have many points of re- 

 semblance to the existing Gavials. 

 In the Cretaceous rocks, lastly, 

 and especially in the estuarine de- 

 posits of the Wealden, we have 

 various types of Amphicoelian Cro- 

 codiles, such as Goniopholis, Pholi- 

 doscmrus, and Diplosaurus. The 

 genus Hyposaiirus is found in the 

 Cretaceous of North America, and 

 its species resemble in form the 

 modern Gavials. 



We may briefly consider here a 

 group of Reptiles which have been 

 regarded as Crocodilian, but wdiich 

 are placed by Owen in a separate 

 order under the name of Thcco- 

 dontia, and which are looked upon 

 by Huxley as being Dcinosaurian. 

 The " Thecodont " Eeptiles are de- 

 fined as follows : " Vertebral bodies 

 biconcave ; ribs of the trunk long 

 and bent, the anterior ones with a 

 bifurcate head ; sacrum of three 

 vertebrae ; limbs ambulatory, femur 

 Teeth with the crown more or less 

 compressed, pointed, with trenchant and finely serrate mar- 

 gins, implanted in distinct sockets." — (Owen.) 



Omitting Bclodon, now generally regarded as Crocodilian, 

 the Thecodont Reptiles are the Thecodontosaurus and Palcco- 

 saurus (fig. 563) of the Trias. These were orginally based 



Fig. 562. — Skull of Stencosanriis lie- 

 herti, viewed from above. Jurassic. 

 Actual length about three feet and ;i 

 half. (After Morel de Glasville.) 



with a third trochanter. 



