198 REPTILES AND BATRACHIANS 



born In an advanced larval condition, w^hile a few^ never 

 go near w^ater, even for breeding purposes, the young 

 leaving the egg or uterus in the perfect form. 



Sexual maturity is reached in most Batrachians in the 

 third or fourth year of their existence. Most Tailless 

 Batrachians, during the breeding season, are notorious 

 for the loud sounds w^hich the males produce by means of 

 their vocal sacs, and to which the female responds by mere 

 grunts ; although vocal sacs are absent in all Urodeles, 

 they are not absolutely dumb, producing at times more or 

 less distinct squeaks. 



Fig. 13. — European Tree-Frog, Hyla arborea, 

 showing inflated vocal sac. 



[After Boulenger.^ 



The vocal sac, characteristic of the males of many 

 Tailless Batrachians, frequently forms one or two bladder- 

 like pouches, into which the air penetrates by one or two 

 small openings or slits in the floor of the mouth. The 

 pouch, when the animal croaks, becomes blown out to a 

 very considerable extent, and may, as in the European 

 Tree Frog, attain almost as large a size as the creature's 

 body. The voice of Frogs and Toads varies very con- 

 siderably, and affords the collector a means of ascertaining 

 the whereabouts of the different species. 



The power of regenerating lost parts is possessed by the 

 Urodeles and the tadpoles of the Anures. Newts are 

 able, throughout life, to regenerate both the tail and 



