ii] FEATURES OF ENVIRONMENT 29 



It is a very interesting fact, over which one may 

 ponder deeply, that where parachuting is such a 

 fashionable contrivance as it is in the Indo-Aus- 

 tralian countries, prehensile tails are almost absent. 

 The reverse is the case in the tropical American 

 forests in which there does not occur a single instance 

 of a parachute. 



Intensely arboreal life leads to many other, some- 

 times most unexpected, habits, structural modifica- 

 tions, and sometimes to limited distribution. The 

 scroll-like receptacles of leaves, before mentioned, 

 hold water and some frogs use them as nurseries, or 

 they glue the leaves together, fill the space with a 

 foamy lather and deposit their eggs therein, the 

 development of which is so accelerated that the 

 babies are hatched as tiny frogs, having dispensed 

 with the tadpole stage. Or the male glues the few 

 but large eggs on to the female's back, a trick com- 

 mon in Africa and on the Seychelles. In some 

 Brazilian tree-frogs a slight fold of skin is raised 

 along the sides of the back, to prevent the eggs from 

 slipping off. In some other kinds these folds enlarge 

 during the hatching season into a kind of hood, e.g. in 

 Hyla goeldi. In a few tropical Americans this hood 

 has become a permanent organ, a pouch on the back. 

 Nototrema is the generic name of these marsupial 

 frogs ! It has been suggested, upon weighty reasons, 

 that even the marsupial mammals owe their survival 



