CLASSIFICATION OF REPTILES. 5 



we have hitherto discussed. They possess five senses, a heart, a 

 circulation, with red blood. 



We have now to deal with a class advanced above that of fishes, 

 that of Reptilia, which is divided as follows : — 



Amphibia — (Batrachia, Cuv.) 



Animals having ribs or processes, or short, slight, and free ver- 

 tebrae, forming a series of separate centrums, deeply cupped at both 

 ends, one of which is converted by ossification in the mature animal 

 into a ball, which may be the front one, as in the Surinam Toad, 

 Pipa; or the hind one, in the Frogs and Toads, Rana. The skin is 

 nude, limbs digitate, gills embryonal, permanent in some, in most 

 lost in metamorphosis, to be succeeded by pulmonary respiration, or 

 both ; a heart with one ventricle and two auricles. They consist of : — 



I. Ophiomorpha. 

 Casciliaclse or Ophiosomse. 



II. ICTHYOMORPHA. 



Proteidae or Sirens, Proteus, Newts, and Salamanders. 



III. Theriomorpha. 



Aglossa . . . Pipa or Surinam Toads. 



Ranidce . . . Frogs. 



IlylidcB . . . Tree Frogs. 



Bufonidce . . Toads. 



Chelonia, or Turtles. 



Distinguished by the double shield in which their bodies are 

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



The Turtles, Chelonia, have the limbs natatory. 

 Mud Turtles , Trzonyx, J u amphibious, 

 lerrapens, iLtnys, ) r 



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, Lizards ; having ambulatory limbs. 



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



