AMEEICAN BATS OF THE GENERA MYOTIS AND PIZONYX 37 



Color paler. 



Size maximum for the species ; greatest length of skull 15.8 to 

 17.6 mm. (Kansas, through Texas and New Mexico, to 



Durango) M. v. incautus (p. 92). 



Size minimum for the species; greatest length of skull 14.2 to 



15.6 mm. (Lower California M. v. peninsularis (p. 93). 



Cheek teeth normal, the breadth of the maxillary molars as compared 

 with the intervening palate not greater than usual in American 

 members of the genus. 

 Fur above dense, wooly ; a low but evident sagittal crest always 

 present in adults (Florida; Indiana; Saskatchewan?). 



M. austroriparius (p. 76). 

 Fur above normal, silky ; a sagittal crest rarely present. 

 Fox-earm ranging from 32 to 37 mm. ; greatest length of skull 

 ranging from 13.2 to 14.2 mm.; hairs of back without con- 

 spicuous burnished tips (western North America). 



M. yamanensis (p, 61). 

 Color paler. 



Above pale buffy, below almost white (deserts of Great 



Basin) M. y. yumanensis (p. 65). 



Above tawny olive, below dull whitish, tinged with buffy 



(western United States) M. y. sociabilis (p. 68). 



Color darker. 

 Membranes and ears blackish brown, fur dull sepia above 



(northwest coast) M. y. saturatus (p. 70). 



Membranes and ears dull brownish, fur dark cinnamon 



brown above (southern Mexico) M. y. lutosus (p. 72). 



Forearm ranging from 36 to 40 mm. ; greatest length of skull 

 ranging from 14.3 to 15.3 mm. ; hairs of back with conspicu- 

 ous burnished tips (North America in general). 



M. lucifugus (p. 38). 

 Small premolars unusually crowded (Mexico and western 



Texas) M. 1. fortidens (p. 54). 



Small premolars not unusually crowded. 

 Color above ranging from blackish to very dark brown 



(northwest coast) M. 1. alascensis (p. 47). 



Color not ranging from blackish to very dark brown. 

 Belly with a distinct bufiCy wash ; membranes not edged 

 with white (region east and north of Rocky Moun- 

 tains) M, 1. lucifugus (p. 43). 



Belly whitish ; membranes edged with white. 



General color above cinnamon buff, ears black, edges 

 of membranes often whitish (semiarid western 



United States) M. 1. carissima (p. 50). 



General color above pale pinkish buff, ears pale brown- 

 ish (Great Basin) M. 1. phasma (p. 53). 



