344 



GENERAL ZOOLOGY 



species of tree-frogs from South America (Nototre'ma) the 

 females possess dorsal pouches in which the eggs are placed. 

 The young appear either as tadpoles or as perfect frogs. 



The tree-frogs or tree-toads are forms adapted to an arbo- 

 real existence. They possess soft pads on the end of the 



digits. Many of 

 them, like our 

 common tree-toad 

 (Hyla versic'olor, 

 Fig. 171), are pro- 

 tectively colored, 

 and have the 

 power of chan- 

 ging their color 

 through various 

 shades of gray and 

 green. A South 

 American species 

 is conspicuously 

 marked with red 

 and blue. Experi- 

 ments seem to 

 show that it is so 

 well protected by 

 an acrid secretion 

 that it is not fed 



upon by birds, which might otherwise devour it. Several of 

 our smaller species of tree-toads, called " peepers " in the 

 country, give utterance to shrill notes, which are among the 

 first sounds of spring. In that season they seek the ponds to 

 mate and lay their eggs. 



The common toad (Bu'fo lentigino'sus) is one of the farmers' 

 most valuable allies in the destruction of injurious insects. 

 Despite the prejudice which its appearance still excites among 



Fi<;. 171. Photograph of Tree-Frog. Reduced 



