AMERICAN BATS — HANDLEY 



117 



9), a lobe that is present, although small and inconspicuous, in P. 

 auritus but absent in P. townsendii. Modification also occurs in the 

 primary anterior basal lobe, where variation ranges from reduction in 

 P. townsendii to no modification in P. phyllotis and enlargement in 

 P. auritus (fig. 9). 



Thus, with regard to the dental, osteological, and external charac- 

 teristics of these bats, it appears that P. (Idionycteris) phyllotis is the 

 most generalized and primitive member of the group; P. {Coryno- 

 rhinus) townsendii is most specialized and progressive ; and P. {Plecotus) 

 auritus is intermediate (but nearer P. townsendii). 



Comparison of Plecotus with other vespertilionine genera confirms 

 the observation that the differences among its species are, at most, 

 of no more than subgeneric magnitude, Myotis, Pipistrellus, and 



PLECOTUS I CORYNORHINUS ) 



TOWNSENDII 

 USNM K8550 



PLECOTUS ( PLECOTUS ) AURITUS 

 USNM 86601 



MYQTIS VELIFER 

 USNM 102472 



Figure 7. — Muzzles of Plecotus, compared in anterolateral aspect with the muzzle of 

 Myotis, a generalized vespertilionid. Camera lucida sketches. 



