October, 1902.] MAMMALS OF KEEWATIN. 53 



the tide to come in that wo miglit resume our journey southward. 

 This series includes j^oung and adults of all ages and both sexes, the 

 females slightl\- predominating. Several females contained embr^yos 

 which varied in number from seven to ten. 



Ten specimens taken on the 'Barrens,' near Cape Churchill, August 

 25, are referable to this form, and the large series of driniuiiondit&Ven 

 at Fort Churchill includes some specimens that seem to incline toward 

 aphorodem ii.t. 



Microtus xanthognathus (Leach). Chestnut-cheelted Vole. 



This species was originally described from Hudson Bay. During 

 our trip, though constantly on the lookout for the species, we saw no 

 traces of voles which we could attribute to .rantliogiudluM and secured 

 no specimens. 



Coues recorded Arvicola .mnthor/natlnis from Fort Churchill." The 

 fact that the table in which this specimen is listed contains only skins 

 with chestnut cheeks, as shown by the context, makes it evident that 

 the identification is correct, a fact further supported by the length of 

 the hind foot (1 inch). This specimen can not now be found. Bailey 

 records Microtus a'fodJwgnathus from Nelson River.* 



Fiber zibethicus hudsonius subsp. nov. Hudson Bay Muskrat. 



Type from Fort Churchill, Keewatin, Canada. $ ad. (skin and skull), No. 

 106881, U. S. Nat. Mus., Biological Survey collection. Collected August 9, 

 1900, bj' Alfred E. Preble. Original number, 3081. 



Geney^al character. — Rather small, about the size of Fiber sjMtulatus, 

 but differing in color and cranial characters; smaller than and other- 

 wise different from Fdx-r zihethicus. 



Color. — Above, dull yellowish brown, darker on middle of back and 

 head; fur of lower jjarts tipped with yellowish brown, throat yellow- 

 ish white; middle of chin dusky; cheeks yellowish fawn. Compared 

 with spatulatus, hudsonius is more yellowish brown, the back lacking 

 the duskj^ tinge of xj'atidatus, and the sides are uniformly lighter. 



Skull. — Smaller and more angular than in Fibe?' zibethicus, with 

 highly developed interorbital crest and small molars, as in sjMtidatiis, 

 but differing from skull of qxdidatits as follows: BuIIsb more inflated; 

 parieto-squamosal suture irregular; lateral face of z3'goma, especially' 

 jugal, broader; nasals narrower anteriorly, but otherwise similar. 



Measurements. — Type: Total length 539; tail vertebrte 225; hind foot 

 74. Average of four adults from Echimamish River: Total length 642. 5; 

 tail vertebrae 236.2; hind foot 75.7. Average of two adults from 

 York Factorj': Total length 556; tail vertebrse 246.5; hind foot 74.5. 

 Skull of type: Occipito-nasal length 56; zj^gomatic breadth 38; inter- 

 orbital breadth 6; greatest length of nasals 20; greatest breadth of 

 nasals 9.5; length of upper molar series (crowns) 13.5. 



«Mon. N. Am. Rod., p. 201, 1877. (No. 8356 in table.) 

 6N. A. Fauna, No. 17, p. 58, 1900. 



