DERIVATION OF THE FLORA OF HAWAII 33 



tralasian elements in the fauna, Wallace's view would appear the more 

 probable. 



The other passerine families are the Turdidae with a single genus, 

 Phaeornis, and the Muscicapidae (Old World Flycatchers) with a single 

 genus, Chasiempis. 



Perkins believes that these forty-nine passerine birds are the de- 

 scendants of six, possibly seven, ancestral species, of which possibly 

 two gave rise to the Drepanididae. The extraordinary evolution of the 

 species of this family and their highly specialized character indicate that 

 they have been in the islands for a very long period. 



Wallace says that the Drepanididae are "the remains of a larger and 

 more varied family once inhabiting more extensive land surfaces in the 

 Pacific." 



MAMMALS 



With the exception of a single bat, all of the mammals probably owe 

 their presence in the islands to human agencies. 



