IV.] THE COMMON FROG. 37 



CHAPTER IV. 



Having now passed in review the greatest differ- 

 ences presented by the nearest allies of our common 

 Frog (the members namely of its own order), certain 

 facts of interest present themselves respecting the 

 geographical distribution of the group Anoura. These 

 facts are interesting, because they point not only to 

 the exceptional nature of the faunas of South America 

 and of Australia, but also to a certain zoological 

 affinity between those two regions of the earth, 

 distinct as they are from one another. Thus, as has 

 been mentioned, it is only in Australia and South 

 America that the typical genus Rana is absolutely 

 wanting. One genus of Tree-frogs, Pelodryas, is con- 

 fined to Australia, but is closely resembled by another 

 genus, Phyllomcdusay which is restricted to South 

 America, and differs from the former only by the 

 absence of a web between the toes. It should be 

 recollected that the primary subdivisions of a zoo- 

 logical order are X.^xm.^di families. One whole family, 

 called Cystignathidcs, is (with the exception of two 

 species) confined to Australia and America. 



The typical Tree-frogs {Hyld) abound in South 



