52 NORTH AMERICAN FAUNA. [No. 22, 



This series averages a little larger than tj^pical drununondt, but on 

 the whole is fairly typical. Seven adults from Norway House aver- 

 age: Total length 152; tail vertebras 42; hind foot 19. Seven from 

 Oxford House average: 153; 47; 19. Seven from Fort Churchill 

 (selected as being nearly typical of this form): 156; 40; 19. 



Microtus aphorodemus sp. nov. Barren Ground Vole. 



Type from Barren Grounds, about 50 miles south of Cape Eskimo, Keewatin 

 (near mouth of Thlewiaza River). 9 ad. (skin and skull). No. 106422, TJ. S. 

 Nat. Mus., Biological Survey collection. Collected August 5, 1900, by Edward 

 A. Preble. Original number, 3208. 



General characters. — Similar to Microtwi druvnnond!, but larger, 

 with much larger and heavier skull. 



Color. — Upperparts dark yellowish bister, as in drumniond!, but 

 usually with an admixture of j'ellowish- tipped hairs, imparting a 

 coarse appearance to the pelage; adults varj'ing beneath from nearly 

 white to light plumbeous, sometimes tinged with light brownish. 

 Young: Var3'ing but little from adults, lighter in color than young 

 of druinmondi, especially beneath. 



Sl'ull. — Much larger than that of drununond'i ; rostrum propor- 

 tionally heavier; molar series longer. Compared with that of jitnn- 

 sylvanicus the skull is much larger, less arched, and with more widely 

 spreading zygomata; teeth about as \n jyennsylvanicus. 



Measurenumts. — Type: Total length 190; tail vertebrje 50; hind 

 foot 20. Average of six adults from type localit^^: 182; 49; 20.3. 

 Average of four adults from near Hubbart Point: 181; 49; 20.2. 

 Skull of type: Basal length 2S; nasals 7.6; zygomatic breadth 16.5; 

 mastoid breadth 12.6; alveolar length of upper molar series 7. Skull, 

 No. 106274, 9 ad. (largest in series): Basal length 29; nasals 8.5; 

 zj'gomatic breadth 17; mastoid breadth 12.5; alveolar length of upper 

 molar series 7. 



Heniarl'x. — I found these voles common on the Barren Grounds near 

 the mouth of Thlewiaza River early in August, and collected a 

 large series. They frequented patches of wild rye [Elymus mollis) 

 on the sandy raised sea beaches near the shore, and burrowed exten- 

 sivelj" in the sand and to some extent in the semidecayed musses of 

 seaweed which had accumulated at high-water mark. They were 

 most active in the morning and evening, but were taken at all hours 

 without difficulty in traps set in their well-worn trails. Their prin- 

 cipal food seemed to be the culms of the wild rye. I found many 

 cavities beneath boulders which they had utilized for storehouses and 

 had filled with the stalks of this coarse grass, cut into short sections. 



Along the coast north of Fort Churchill at several points where the 

 wild rye grew luxuriantly I found abundant traces of these voles. A 

 series of twenty-two was collected on a point about 10 miles north of 

 Hubbart Point on the morning of August 16, while I was waiting for 



