216 



VERTEBKATA: REPTILIA OR REPTILES. 



The organs of smell are but little developed. The 

 tongue is generally thin and dry, though sometimes fleshy. 

 Their sense of touch is feeble. 



Including both living and fossil species, the true Reptiles 

 comprise the following groups, which for our present pur- 

 poses may be regarded as Orders : * 



1. CHELONIA or Testudinata, or reptiles with a shell and with a 



horny beak instead of teeth ; as Turtles. 



2. DlXOSAURIA, huge fossil reptiles with bird-like, 



and mammalian characteristics ; as Megalosau- 

 rus, Hylceosaurus, Iguanodon, Hadrosaurus, etc. 



3. CROCODILIA, large living reptiles, with a cuirass 



of bony plates, large conical teeth in sockets, 

 vertebrae concave in front, and convex behind ; 

 sacrum generally with two vertebrae, and a heart 

 with four cavities ; as Crocodiles, Alligators, and 

 the fossil Telosaurus, etc. 



4. LACERTIA, reptiles with scales, with the teeth 



not in sockets, and the heart with only three 

 cavities ; as Lizards, fossil Thecodonts, etc. 



5. ExALlOSAURIA, huge fossil saurians furnished 



with paddles for swimming, with biconcave verte- 

 brae, and with large teeth set in a groove ; as the 

 Ichthyosaurus, Plcsiosaurus, etc. The Mososaurus 

 Avas also an Enaliosaur, but with teeth in sock- 

 ets, and the body was covered with bony plates. 



6. PTEROSAUKIA, or fossil reptiles organized for 



flight ; as Pterodactyls. 



7. OPHIDIA, reptiles with no legs, and with no sternum, and no 



eyelids, and no external ear ; as Snakes. 



* The Reptiles are often considered as comprising only three Orders, 

 thus : 



1. CHELONIA or Testudinata. 



2. SAURIA (including Dinosauria, Crocodilia, Lacertia, Enaliosauria, and 

 Pterosauria). 



3. OPHIDIA. 



} SAURIA. 



