BATKACIUA. 53 



others, as adults, are to be sought in moist places. In some 

 forms the external gills are retained permanently. The 

 order belongs almost exclusively to the northern hemisphere, 

 and is especially well developed in America. Allied to these 



FIQ. 20. Salamander (Plethodon). 



forms are some enormous fossils, grouped under the name 

 STEGOCEPHALI, some of which had skulls five feet or more 

 in length. 



ORDER II. ANURA (Frogs and Toads). 



These in the adult condition lack a tail, and have appen- 

 dages fitted for leaping. The lower jaw is without teeth. 

 The larvae are always tailed, and have at first external gills. 

 Frogs and toads differ in that frogs have a smooth skin, and 

 teeth in the upper jaw ; toads have a warty skin (caused by 

 numerous glands) and no teeth. Tree-toads are more frog- 

 like, but they have sucking disks on the ends of the toes, 

 by means of which they are adapted to a life in trees. 

 Another group occurs in the tropics, in which the tongue 

 is absent. 



Some of the Anura have strange breeding habits. Thus 

 in the European Alytes the male wraps the long string of 

 eggs about his body and carries them there until they hatch. 

 In Nototrema of South America the skin of .the back forms 

 a pouch, in which the eggs are carried ; while in the Suri- 

 nam toad (Pipd) the skin of the back becomes very much 

 thickened, leaving little cups, in each of which an egg 

 occurs, and here the young are hatched out, 



