318 



COMPARATIVE ZOOLOGY. 



Proteus of Austria, Menobranchus 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. Ceecilia have neither tail nor limbs, a snake-like form, 



Fig. 295. — Proteus anguinus. Europe. 



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

 are confined to the tropics. 



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

 phibians, as Frogs 

 v^^^P anc ' Toads. They 

 ^^^^^■■IfcBfcfc-H^^C^'^'^^ have a moist, naked 

 ^^^^^^^^^^^^^ skin, ten vertebrae, 



and no ribs. As they 



Fig. 296.— Red Salamander (Pseudotriton ruber). breathe by SWalloW- 

 United States. . . , , (1 



mg the air, they can 

 be suffocated by holding the mouth open. They have 



