AMPHIBIA 



221 



CLASS III. AMPHIBIA 



To this class belong the toads, frogs, sala'manders, and 

 newts. The skin is smooth, as in the frog, or warty, as in the 

 toad, with a glandular secretion. "One group, however, possesses 

 minute scales, but some of the extinct Amphibia were provided 

 with well-developed bony plates in the 

 integument." — Weysse. It is often 

 highly colored owing to the pigment 

 cells in the deep layers. In the com- 

 mon "tree-toad," as well as in some of 

 the terrestrial frogs, the color may be 

 changed to harmonize with the en- 

 vironment. No amphiljians are ma- 

 rine. Most of them are aquatic or 

 semi-aquatic. In the adult stage some 



Fiji. 1S2.— Hullfros. (Skeleton Fig. l8S.— Necturm. (Skeleton 



cleaned and mounted by stu- cleaned and mounted by stu- 

 dents.) dents.) 



are terrestrial, some arboreal. They are usually carnivorous in 

 the adult stage, but the larva; may be herbivorous. They hiber- 

 nate in the mud at the l.)ottom of a stream and may live a long 

 time without food. They make fine specimens for study in a tank 

 or tub, since many of them will endure captivity a good while. 



