150 MICROTINJE 



washed with a bright reddish-chestnut brown, much as in D. t. tor- 

 quatus. Under parts, feet and tail whitish. 



For external and cranial measurements see tables at end of 

 volume. 



Remarks. — The descriptions of this animal, given by von Baer, 

 Middendorff and Heuglin, and the figure published by the latter, 

 seem sufficient to prove its distinctness from D. t. torquatus. 

 Pending the acquisition of modern material it may be regarded 

 as a subspecies of D. torquatus, but its precise status is 

 doubtful. 



2. Dicrostonyx chionopses Allen. 



1914. Dicrostonyx chionopcBS G. M. Allen, Proc. New England Zool. 

 CI., 5, p. 62. 



Type. — Museum of Comparative Zoology, Harvard Coll. 



Type locality. — Nijni [Nischne] Kolymsk, near the mouth of 

 the Kolyma River, N.E. Siberia. 



Range. — Known only from the type locality. 



Characters. — Smaller than D. torquatus (total length only 

 116 mm.), but with a relatively large skull (condylo-basal length 

 27-5 mm.). 



Head and body length unusually small, scarcely exceeding 

 100 mm. Hind-foot relatively very large, 20 mm. Summer 

 pelage imperfectly known ; winter pelage pure white as usual. 



The type and only known specimen, is an adult male collected 

 October 15, 1911, which has nearly completed its change into the 

 winter dress. The only remnants of the summer coat remaining 

 are a small patch of hazel on the top of the head and nape, 

 another on the centre of the chest, and a concealed substratum 

 of russet-tipped hairs with a few black hairs intermixed in the 

 mid-dorsal region. Middle fore-claws already much enlarged. 



Skull. — The skull is described as " quite adult with the 

 basioccipital suture solidly fused and ridged." In relation to 

 the size of the animal it is very large; only slightly smaller in 

 all respects than the skull of D. torquatus from the Taimyr 

 Peninsula figured by Middendorff. Interparietal nearly rectan- 

 gular, without an anterior median projecting point. Cheek-teeth 

 not described, but presumably as in D. torq^iatus. 



For external and cranial measurements, see tables at end of 

 volume. 



Remarks. — It is to be hoped that further material will be 

 obtained. The hind-foot measurement is so large in proportion 

 to the total length that one is almost tempted to believe that an 

 adult skuU has by some error been allocated to an immature skin. 

 Assuming that no such mistake can have been made, this is a form 

 of extraordinary interest. 



Baird (Mamm. N. America, p. 559, 1857) says : " The N. P. 

 Exploring Expedition, under Captain Rogers, collected specimens 



