6 INTEODUCTOET. 



III. Theeiomoepha. 

 Agloasa . . , Pipa or Surinam. Toads. 

 Ranidfe . , . Progs. 

 Hylidis . , . Tree Frogs. 

 Bufonidce . . Toads. 



Chelonia, or Turtles. 

 Distinguislied by the double shield in wbicb tbeir bodies are 

 enclosed, whether they are terrestrial, fresh- water, or marine. 



The Turtles, Chelonia, have the limbs natatory. 



Mud Turtles, Triomix, 1 ,. , , ., - 



_ ' ! limbs amphibious. 



Terrapens, Bmys, ) 



Tortoises, Testudo, limbs terrestrial. 



Lacertilia. 

 Having a single transverse process on each side, single-headed 

 ribs, two external nostrils, eyes with movable lids ; body covered 

 with horny, sometimes bony, scales. 



Lacerta — the Monitors, Crocodiles, Lizards ; having ambulatory limbs. 

 Anguis — Ophisaurus, Bimanus, Chalcides, Seps ; limbs abortive ; no sacrum. 



Ophidia. 

 Having numerous vertebrae with single-headed hollow ribs, no 

 visible limbs, eyelids covered by an immovable transparent lid ; 

 body covered by horny scales. It includes : — 



Viperince — the Vipers and Orotalidae. 

 Colubrina: — the Colubers,, Hydridse, and Boidse. 



Crocodilia. 

 Teeth in a single row, implanted in distinct sockets ; body de- 

 pressed, elongated, protected on the back by solid shield ; tail 

 longer than the trunk, compressed laterally, and furnished with 

 crests above. The several families are : — 



Crocodilidne — the Gavials, Mecistops, Crocodiles. 

 Alligatoridts — Jacares, Alligators, Caiman.* 



* By some naturalists the Awphibia are considered as a distinct class, by other 

 as a sub-class either of Reptilia or of Pisces. Of the reptiles proper (at present 

 existing), the arrangement into the orders Testudinata (or Tortoises), Sauria (or 

 Lizards), and Ophidia (or Snakes), is the one most generally adopted ; but De Blain- 

 Tille elevates the Loricata (or Crocodiles) to the rank of an order, and others have 

 adopted a division of corresponding rank, Saurophidia, for the Anguis series above 

 referred to ; but the latter are merely limbless Lizards (or with abortive limbs) akin 

 to the Scinques. — En. 



