364 MOSTLY MAMMALS 



a tree-frog (Hyla abbreviatd) have been observed adhering 

 to rocks by means of the flat surface of the abdomen, 

 which acts as a sucker. Nothing is, however, known with 

 regard to the eggs. 



In all the foregoing instances the peculiarities of develop- 

 ment are confined to the situations in which the spawn 

 is deposited and the tadpoles are developed. There is, 

 however, another and far more remarkable class of cases 

 in which the bodies of either the male or female parent 

 are specially modified to act as receptacles for the eggs 

 and tadpoles. The best instance of this class is that of 

 the well-known Surinam toad (Pipa americana}* in which 

 the eggs are evenly distributed, as they are laid, over the 

 back of the female by the male. Around these the skin 

 of the back speedily thickens until each egg is enclosed in 

 a separate cell, furnished with a lid. The eggs hatch in 

 about eighty-two days, and the young are stated to find 

 safety and nourishment on the parental back until their 

 transformation is completed. The limbs make their appear- 

 ance at an unusually early age, even before the external 

 gills are shed. 



Equally remarkable are the " nursery " arrangements of 

 the pouched frogs (Nototrema) of South America. In these 

 frogs the back of the female is furnished with a long tube- 

 like pouch, having its opening at the posterior end. In 

 this pouch the eggs, which are about fifteen in number, 

 are deposited and hatched ; and the tadpoles also undergo 

 the whole of their metamorphosis in the same chamber. 

 In some cases, at least, the pouch splits longitudinally 



* The breeding habits of this and some of the following forms have 

 been already referred to in a previous article ; but, in order to render 

 the present one complete in itself, it has not been considered advisable 

 to eliminate such repetition as may exist. 



