36 BULLETIN 144, UNITED STATES NATIONAL MUSEUM 



Foot normal or large, the ratio of its length to that of tibia usually ranging 

 from about 48 to 60. 

 Wing membrane attached to tarsus ; fur of back without obviously darkened 

 basal area; ratio of foot to tibia usually about 60 (Indiana and Illinois 



to Alabama and Georgia) M. grisescens (p. 80). 



Wing membrane attached to side of foot; fur of back with obviously dark- 

 ened basal area ; ratio of foot to tibia usually less than 57. 

 Fur of back with an obvious tricolor pattern ; calcar usually with a small 



but evident keel (eastern United States) M. sodalis (p. 130). 



Fur of back without an obvious tricolor pattern ; calcar normally with 

 no trace of keel. 

 Ear when laid forward extending noticeably beyond tip of muzzle. 

 Free border of uropatagium with inconspicuous, scattered, stiff hairs 



(central and northern North America) M. keenii (p. 101). 



Color darkened ; a saturate northwest coast form. 



M. k. keenii (p. 104). 

 Color normal ; a normal eastern and central form. 



M. k. septentrionalis (p. 105). 



Free border of uropatagium usually with a noticeable fringe of stlflE 



hairs. 



Size larger, forearm usually 41 to 46 mm. ; ear not exceptionally 



enlarged; fringe conspicuous (Mexico and western United 



States) M. thysanodes (p. 122). 



Under parts whitish, upper parts "warm buff" (western United 



States and northern Mexico) Iff. t. thysanodes (p. 126). 



Under parts huffy, upper parts darker, " tawny olive " (southern 



Mexico) M. t. aztecus (p. 128). 



Size smaller, forearm usually 33 to 40 mm.; ear exceptionally en- 

 larged; fringe not conspicuous (western United States and 

 northern Mexico). 

 Skull with noticeably flattened brain case; forearm 33 to 36 (San 

 Pedro Martir Mountains, Lower California). 



M. milleri (p. 118). 

 Skull with normal brain case ; forearm usually 37 to 40. 



M. evotis (p. 111). 

 Upper parts darker, near clay color (northwest coast region). 



M, e. evotis (p. 114). 

 Upper parts lighter, flaxen or cinnamon buff (range of the 

 species except northwest coast region). 



M. e. chrysonotus (p. 116). 

 Bar when laid forward not extending noticeably beyond tip of muzzle. 

 Cheek teeth robust, the breadth of the maxillary molars, as com- 

 pared with that of the intervening palate, greater than usual 

 in American members of the genus. 

 Brain case flattened; pelage glossy (southwestern United States). 



M. occultus (p. 97). 



Brain case highly arched; pelage dull M. velifer (p. 86). 



Color darker (Mexico and western United States). 



M. V. velifer (p. 89). 



