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. Ccecilia 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. Batracliia 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 bv SWalloW- 
United States. . / 
ing the air, they can 
be suffocated by holding the mouth open. They have 
