96 



HIGH SCHOOL ZOOLOGY. 



Fig. 70.— Stages in the Development of an European toad. (Pelobates). 



o. the gelatinous spawn containing developing eggs, o'; a. a group of tadpoles adhering 

 to a weed ; b. one of these enlarged showing the external gills ; c. stage in which ex- 

 ternal gills are lost, the spiral intestine is represented ; in d, the hind, and in e, all four 

 limbs are developed, while the tail is shrivelled up in f amd lost entirely in g. 



22. In III, 16, three genera of Anura are mentioned which 

 form the types of so many families of Anura. The Ranidae are 

 characterized by the great length of the hind limbs, by the 

 presence of teeth in the upper jaw, and by the smooth skin — 

 the Bufonidae on the other hand, have shorter legs, a warty 

 skin and no teeth, while the Hylidse are specially marked out by 

 the adhesive disks with which the fingers and toes are provided, 

 and which permit the climbing habits of the genus. Two 

 species of Hyla, one of Bufo, and five of Rana occur in our 

 region. The largest of the latter is the bull frog (R. catQsbyana) 



