260 PROCEEDINGS OF THE ACADEMY OF [1894. 



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ll'O; incisor to post-palatal notch, 12-4; length of mandible, 14*5; 

 greatest width of mandible, 6'8. 



Two adult, nursing females of this species, were sent to Mr. 

 Fletcher, of the Ottawa Experimental Farm, by Mr. Keen, and 

 were forwarded to me in spirits. Their grayness, large size, and 

 long tails serve to distinguish them externally from any other 

 boreal or northwestern form I know of. Eight specimens of Sitoiiujs, 

 trapped at an elevation of 6,000 feet, on the Cascade Mountains of 

 northern Washington, are, perhaps, referable to this species. They 

 depart therefrom in somewhat smaller size, but in all other respects 

 are much nearer to it than to aiisterus, of Puget Sound. The climatic 

 conditions of the Cascades where these were taken, are, with the 

 exception of a more rigorous winter, quite the same as those pre- 

 vailing at Skeena Harbor, the type locality of viacrorhiuus. 



6. Sitomys americanus artemisiae sp. nov. Type, Xo. 368, ad. ^ , Coll. S. N. 

 Khoads. Ashcroft, J5ritish ('oluoil)ia, June fith, 1802. L'ol. by S. N. R. 



Description. — Size large, exceeding typical americanus. Tail 

 short, hardly equalling body without the head. Ears medium and 

 sparsely haired. The hind feet are small and densely haired to the 

 distal half. Colors above, tawny ash, inclining to fulvous on sides 

 and rump and darkening with an increase of blackish hairs along 

 the back. Upper third of tail sooty, the lower two-thirds white and 

 tipped with a pronounced pencil. Lower parts a soft, clear white, 

 with basal half of belly hairs plumbeous. 



3feasureinenfs. — Total length, 170 mm ; tail vertebrio, 70 ; hind 

 foot, 20 (average of 8 adults — Total, 164; tail, 68; foot, 20). 

 Skull — Total length, 26; basilar length, 20; zygomatic width, 102; 

 length of nasals, 11*1; incisor to post- palatal notch, 11; length of 

 mandible, 14; greatest width of mandible, 6.8. 



The nearest ally of this subspecies is probably S. a. nebrascensis, as 

 defined by Dr. Mearns,* from specimens taken at Calf Creek, INTontana, 

 from which it differs in not having dark well-haired ears and in the 

 absence of white patclies in front of ears. With nebr(i.'<censis it coin- 

 cides in short tail, larger body, long full pelage, hairy sole, and light 

 colors as contrasted with americanus of the east and austerus of the 

 west. The Ashcroft specimens represent the northern limit of a 

 Great Basin form of americanus, whose habitat probably extends far 



* Bull. Amer. Mus. N. H., Vol. II, Art. xx, 285. 



