70 SEX AND HEREDITY 



In the most interesting attempts on the part of frogs 

 and toads to free their life-history from the aquatic 

 environment, the eggs or young are carried about by the 

 parent. In the case of Alytes, a Toad common on the 



FIG. 39. 



Male of Phyllobates tnnitatis, carrying Tadpoles. (From Graham Kerr's 

 Embryology, after Boulenger.) 



continent of Europe, the eggs are laid on land, and the 

 male parent carries them about in a mass, composed 

 really of two bead-like strings, attached round his legs. 

 At intervals he visits a pool of water and the eggs are 

 moistened ; eventually, on one of these visits, the tadpoles 

 hatch out and thereafter lead a normal aquatic existence. 



FIG. 40. 



Female of Hyla gceldii, carrying eggs. (From Graham Kerr's Embryology, after 



Boulenger.) 



In various other cases the tadpoles j ourney on land from 

 one pool to another, hanging on to the back of the male 

 parent (Fig. 39). In a Brazilian Tree-frog Hyla goeldii 

 the eggs are placed on the back of the female, and their 



