318 



COMPARATIVE ZOOLOGY. 



Proteus of Austria, MendbraricKua of the eastern United 

 States, and the two-legged Mud-eel (Siren) of South Car- 

 olina. Others drop their gills, and always have four limbs, 

 as the aquatic Newts and land Salamanders. 162 The fore 

 limbs first make their appearance in the tadpole. 



2. Labyrinthodontia^ now extinct, resembled gigantic 

 Salamanders, except in their complex teeth and exoskele- 

 ton of bony plates. 



3. CcBcilia have neither tail nor limbs, a snake-like form, 



They 



FIG. 295. Proteus anyuinits. Europe. 



minute scales in the skin, and well-developed ribs. 



are confined to the tropics. 



4. BatracMa include all the well-known tailless Am- 



phibians, as Frogs 

 and Toads. They 

 have a moist, naked 

 skin, ten vertebrae, 

 and no ribs. As they 



FIG. 296. Red Salamander (Pseudotriton ruber). breathe by BWftlloW- 

 United States. 



ing the air, they can 

 be suffocated by holding the mouth open. They have 



