FIELD BOOK OF PONDS AND STREAMS 



salamanders the lips of the cloaca are swollen and wrinkled 

 and in some species the males have keeled tails and on the 

 inner sides of their hind legs the skin is thick and blackish 

 (Fig. 288). 



In spring, frogs and toads congregate in the ponds and their 

 voices, chiefly male, join in the famiHar choruses. They mate 

 soon after they reach the water. Climbing upon the back of 

 the female the male clasps her behind her forearms, and 

 presses his homy thumb and finger pads against the sides of 

 her body. The two continue in this position for hours, often 

 for several days. They do not eat and, although usually 

 shy, at this time they can easily be picked up in the hand. 

 When they are caught the male generally keeps his tight hold 

 on the female even when the pair is roughly handled. Under 

 natural conditions, as soon as the eggs leave the body of the 

 female the male sheds the sperm cells and fertilization takes 

 place in the open water; then the pair separate. 



Many male salamanders deposit gelatinous capsules of 

 sperm cells, the spermatophores (Fig. 289), upon twigs and 

 leaves in the pond. While this is going on the female follows 

 the male about and clasping the sperm-filled top of one of 

 these between the lips of her cloaca, pulls it inside where the 

 sperm cells are stored in special sacs (spermathecas) until the 

 eggs are fertilized. Among the spotted newts and other sala- 

 manders an elaborate courtship precedes the depositing of 

 the spermatophores. 



Life history. — Although different species have their own 

 peculiarities, amphibian life histories are in general very much 

 alike. The young forms or larvae are fish-shaped, with tail- 

 fins and gills. Very young toad and frog tadpoles have 

 suckers by which they can suspend themselves well up in the 

 water where there is plenty of ox3'gen and no mud; most 

 young salamander larvas have "balancers" and their gills are 

 large and bushy (Fig. 286). Transformation to the adult 

 form progresses slowly, the time required differing greatly in 



350 



