L82 



THE AMERICAN NATURALIST [Vol. XLVII1 



TABLE I 



HBUTION AND SPECIATION OF FAMILIES OF CHIROPTERA 



Data Derived from Sclater and Sclater (1899) 



PhyUotomkbi Neotropical 1 36 81 | 2.25 



families is significant. One family, the Vespertilionidae, 

 is cosmopolitan, inhabiting every zoologic region and 

 every life zone, and it has 11.18 species per genus, the 

 highest of any family of bats. The PhyllostomidsB, on the 

 other hand, has the narrowest range, occupying only the 

 warm zones of one zoologic region, namely, the neotropic, 

 and has in 36 genera only 81 species, giving 2.25 as the 



Data Derived from 



index of modification. The other figures in this table are 

 significant, but the indices of modification in the families 

 Bhinolophidae and Nycteridae are abnormally large, and 

 will probably be reduced by subsequent subdivision of 

 genera, or discovery of new forms. 



Table II shows the generic and specific differentiation 



