MICROTUS. 201 



Type locality. Arctic regions " foot of Rocky Mountains," Rich. 

 Jasper House, Alberta, Canada. 



Geogr. Distr. Vicinity of Jasper House and of Henry House, 

 Alberta, Canada. 



Genl. Char. Very large. Tail about as long as head; incisors 

 very large. 



Color. Above dusky dark brown; sides paler; beneath bluish 

 gray; margin of upper lip, chin and feet white. Tail above dark 

 brown, beneath whitish. 



Mc-asurfmtnls. Total length, 208-230 ; tail vertebrie, 50-61 ; 

 hind foot, 28. 



""mm^ffii ^MMm^ 



Fig. -13. MicROTUs (Arvicola) macropus. 



No. 4315 Field Columtiian Museum Coll. Nat. si/e. 



Lower tooth row. Uiu'br tooth how. 



Knlarged 4 limes. Enlarged 4 times. 



a.— macropus. (Arviccla), Mcrr., N. Am. Faun., No. 5, 1891, p. 60. 



Type locality. Pahsimeroi Mountains, Idaho. 



Geogr. Distr. Rocky Mountains from the Wasatch to Canada, 

 the Wind River ranjje of Wyoming, the Blue Mountains of Oregon, 

 and intermediate ranges. High elevations. 



Genl. Char. Size smaller than .)/. richanhcni; tail one-third the 

 length of head and body; hind feet large. Third upper molar with a 

 terminal loop, often recurved. 



Color. Summer Pelage. .Vbove grayish bister lined with black, 

 sides paler; beneath ash gray, base of hairs plumbeous. Tail dusky 

 above, whitish below. Feet dusky. Winter Pelage. Paler above, 

 white beneath. 



Measurements. Totallength,22o;tailvertebrae,7i ;hind foot,26;ear,8. 



