1898.] NATURAL SCIENCES OF PHILADELPHIA. 853 



pale dorsal stripes less sharply defined anteriorly and everywhere 

 mixed with fulvous hairs. 



Measurements. — Type specimen measured in flesh : Total length, 

 210 mm. ; tail vertebra?, 85 mm. ; hind foot, 34 mm. 



Microtus macrurus sp. nov. 



Type. — From Lake Cushman, Olympic Mountains, Washington. 

 No. 66,151 9 ad., U. S. Nat. Mus. Biological Survey Coll. Col- 

 lected June 26, 1894, by Clark P. Streator. Original number 3,975. 



Characters. — Similar to M mordax but larger, with longer tail 

 and decidedly larger hind feet ; color darker. 



Color. — Upper parts brownish bister with a grizzled ' pepper and 

 salt ' appearance, suggesting M. austerus ; under parts whitish, the 

 plumbeous under-fur showing through ; tail bicolor, dusky above, 

 whitish below, the tip sometimes white, sometimes dusky all round. 

 In summer pelage the back is browner and the under parts are 

 washed with buffy. 



Cranial characters. — Skull similar to that of M. mordax, but 

 slightly larger, with rostrum and nasals slightly broader. 



Measurements. — Type specimen : Total length, 220 mm. ; tail ver- 

 tebrae, 88 mm. ; hind foot, 24 mm. Average of 5 specimens from 

 Olympic Mountains: Total length, 204 mm.; tail vertebras, 80; 

 hind foot 24-3, 



Average of 5 specimens of M. mordax from Saw Tooth Lake, 

 Idaho : Total length, 182 mm. ; tail vertebras, 66'5 ; hind foot, 22. 



Remarks. — In coloration Microtus macrurus agrees closely with 

 M. longicaudus from the Black Hills of South Dakota, but in size 

 and proportions it differs from longicaudus even more than from 

 mordax. All three of these animals are very closely related, and it 

 would not be far amiss if both mordax and macrurus were placed as 

 subspecies of longicaudus. 



