TOADS AND FROGS. 



187 



also of Central America, Peters found traces of external 

 gills. The Pipa, or Surinam toad {Pipa Amsricana), 

 which has no tongue, neither teeth in the upper jaw, has 

 similar breeding Iiabits. In this intci'esting toad the young 

 are provided witli small gills, which, however, are of no 

 use to them, as the tadpoles do not enter the water, but 

 are carried about in cavities on the back. The eggs are 

 placed by the male on the back of the female. The female 

 then enters the water; the skin thickens, rises up around 

 each egg and forms a marsupial sac or cell. The young 

 pass through their motamorpiiosis m 

 the sacs, having tails and rudimentary 

 gills; these are absorbed before they 

 leave their cells, the limbs develop, 

 and the young pass out in the form 

 of the adult. 



The toad (Biifo lentiginosus) is ex- 

 ceedingly useful as a destroyer of 

 noxious insects. It is nocturnal in 

 its habits; is harmless, and can be 

 taken up with impunity, tiiough it 



. .. \ ■ 1 a ■ -I J! Fig. 233.— The Martinique 



gives out an irritant acrid lluid irom Tree-toad carrying the 



the skin, which if transferred to tlie yo"°gonis ac . 

 eye or lids occasions some pain. In the Northern States 

 toads begin to make their peculiar low trilling notes from 

 the middle to the 20th of April; from the latter date until 

 the first of June they lay their eggs in long double strings, 

 and the tadpoles are usually hatched in about ten days 

 after tiie eggs are laid. 



Of the true frogs (Rana) there are numerous species; of 

 these the largest is the bull-frog, which makes a deep, 

 hoarse, grunting noise. Smaller and more common species 

 are the pickerel-frog and the marsh-frog. The frogs lay 

 their eggs in roundish masses in ponds and pools from 

 April to June, according to the latitude. 



While most frogs are greedily devoured by herons and 

 other large wading birds, as well as ducks and geese, and 



