3l8 VERTEBRATE ANIMALS OF THE UNITED STATES 



M. nanus (Merr.). Color grizzled gray; length 151 mm.; tail 41 

 mm.; hind foot 18 mm.: Rocky Mountains from central Idaho to 

 central Nevada and southern Colorado; Canadian zone. 



M. n. canescens Bailey. Color lighter and clearer : northern Washing- 

 ton and British Columbia, east of the Cascades. 



M. canicaudus Miller. Color bright yellowish brown; belly whitish 

 gray; tail uniform grayish; length 135 mm.; tail ;^i^ mm.; hind foot 20 

 mm.: Willamette Valley and southern Washington; Transition zone. 



M. dutcheri Bailey. Color dark brown; belly buffy brown; tail 

 bicolor; length 167 mm.; tail 35 mm.; hind foot 20 mm.: Hudsonian 

 zone of the southern Sierras; in wet alpine meadows. 



M. richardsoni (DeKay). Color grayish sepia; belly whitish; tail 

 long; feet large; fur long and heavy; length 234 mm.; tail 81 mm.; 

 hind foot 29 mm.: Boreal zones of the Rockies and the Cascades. 



Subspecies of M. richardsoni 



M. r. macro pus (Merr.). Color dark sepia; size smaller: Rockies 

 from the Wasatch into Canada. 



M. r. arvicoloides (Rhoads). Color dark sepia: Boreal zone of the 

 Cascades. 



M. mogollonensis (Mearns). Color dull rusty brown; belly cinna- 

 mon or gray; mammae 4; length 131 mm.; tail 28 mm.; hind foot 18 

 mm.: plateau country of central Arizona. 



M. oregoni (Bach.). Color dark brown and grizzled; belly dusky; 

 length 140 mm.; tail 42 mm.; hind foot 17 mm.: Pacific coast region 

 from northern California to Puget Sound; in dry open forests. 



M. serpens Merr. Color sooty gray; belly dusky; length 130 mm.; 

 tail 31 mm.; hind foot 18 mm.: northern Washington and southern 

 British Columbia between the Cascades and Puget Sound. 



2. Lagurus Gloger. Similar to Microtus; cranium low and wide; 

 plantar tubercles 5; mammae 8; colors pale; fur lax; tail very short; 

 size small: 4 species. 



L. curtatus (Cope). Color buffy gray; whitish beneath; length 141 

 mm.; tail 27 mm.; hind foot 17 mm.: eastern California and western 

 Nevada; Transition zone. 



L. pallidus (Merriman). Color bufTy gray; length 121 mm.; tail 

 20 mm.; hind foot 18 mm.: western Dakota and Montana, in high 

 prairies. 



L. pauperrimus (Cooper). Color buffy gray; length 115 mm.; tail 

 20 mm.; hind foot 16 mm.: eastern Washington and Oregon; Transition 

 zone. 



