CLASS AMPHIBIA 517 



become air-breathing salamanders of the species Ambystoma 

 tigrinum. 



Family PLETHODONTID.E. All except one species of the 

 eight genera belonging to this family are confined to America. 

 Desmognathus fusca (Fig. 433), the dusky salamander, is a species 

 four or five inches long that lives under stones and in other dark, 

 moist places. The eggs of this species are laid in two long 

 strings which the female takes care of in some place of conceal- 

 ment by winding them about her body. Typhlotriton spelceus 

 is a blind species found in a 

 cave in Missouri. The slimy 

 salamander, Plethodon gluti- 

 nosuSj is common from Ohio 

 to the Gulf of Mexico. It 

 gives off a great quantity of 

 slime when irritated. Autodax 

 lugubris is an inhabitant of 



the western United States. FlG - 433' A lungless salamander, 



Desmognathus fuscus ; female with eggs 



It lays Its eggs in holes in the in a ho i e underground. (From the 

 branches of live-oak trees. Cambridge Natural History, after 



7 ... . Wilder.) 



bpelerpes bilineatus occurs in 



the Atlantic states. The only European species of the family 

 PLETHODONTID.E is Spelerpes fuscus. 



Order 3. Salientia. Most of the AMPHIBIA, about nine 

 hundred species of frogs and toads, belong to this order. They 

 resemble one another very closely and are classified according 

 to the characteristics of certain internal structures. In North 

 America there are seven families and about fifty-six species. 

 Some of them (toads and tree-frogs) live on land, but others 

 (water frogs) spend a large part of their time in the water. The 

 terrestrial species possess only slightly webbed hind feet or no 

 webs at all. They crawl or hop on land, burrow in the earth, 

 or climb trees. Dark, moist hiding places are usually required, 

 and most of them take to water only during the breeding 

 season. 



