DICROSTONYX 149 



Type. — Unknown. 



Type locality. — Region around the mouth of the River Obi, 

 N.W. Siberia. 



Range. — That of the species, excepting the island of Novaya 

 Zemlya. 



Characters. — Essential characters those of the species. 



General colour of adults in summer pelage. — Brownish black 

 above, more or less brightened by the rufous and yellowish sub- 

 terminal bands of the hairs, darkest along the spine, paling to 

 ashy grey on the sides of the head, towards the rump and lower 

 flanks, and upon the outer and lower parts of the limbs. No 

 distinct dorsal stripe ; but a more or less distinct dusky streak 

 upon the top of the head from the tip of the nose to the crown. 

 Ear-tufts, shoulders and humeral regions, together with the 

 foremost parts of the flanks, bright brownish-red, this colour 

 being continued ventrally to form a more or less complete and 

 extensive collar ; the red tint more or less distinctly interrupted 

 by a pallid streak passing upwards from the throat on each side 

 to the region behind the ears. Under parts, apart from the 

 pectoral collar but including the inner surfaces of the limbs, 

 yellowish or dirty white. Feet and tail hairs white. 



For external and cranial measurements, see tables at end of 

 volume. 



D. t. altaicus Vinogradov, described from the Pleistocene 

 cavern deposits of N.W. Altai, is said to be distinguished from the 

 typical subspecies by the structure of m^, which possesses eight 

 instead of seven closed triangles ; but this character is wholly 

 unreliable. Vinogradov himself finds it " not quite constant " 

 in either the fossil or the recent material before him, and if he 

 had been able to examine the enormous amount of fossil material 

 before me he would never have attributed systematic importance 

 to such a detail. 



1^. Dicrostonyx torquatus ungulatus v. Baer. 



1841. Lemmus ungulatus von Baer, von Baer and Helmersen, Beitriige, 



4, p. 283. 

 1853. Myodes lorqualus var. pallida Middendorff, Sibir. Reise, 2, 



Th. 2, p. 93 ; Heuglin, Reisen nach dem Nordpolarmeer, Tlieil, 2, 



frontispiece, 1873, Theil, 3, p. 6, 1874. 



Type.— Unknown. 



Type locality. — Novaya Zemlya. 



Range. — Known only from the type locality. 



Characters. — Essential characters as in the species. 



General colour of adidts in summer pelage. — Upper parts ashy- 

 grey in general colour; with a distinct blackish spinal stripe, 

 running from the root of the tail to the occiput, and continued 

 forwards to the nose by a less definite blackish streak. Ear- 

 tufts, shoulders, foremost parts of flanks, and breast heavily 



