52 BIRDS AND MAMMALS OF EAST SIBERIA [^Vof.'v^* 



Skull and teeth. — The teeth are essentially similar to those of typical 

 araneus of Europe. The first unicuspid, as in that species, is distinctly 

 lower than the second, though with a greater length of crown in side view. 

 The third is markedly smaller than the second, but of nearly the same 

 relative proportions; while the fourth again is much smaller than the third, 

 though of about the same shape. The fifth is minute, but is nearly in the 

 tooth-row. In ventral view the inner posterior lobes of the first incisors 

 are not markedly produced, and are at about the same distance from the 

 mid-line of the palate as are the first unicuspids. The palate is narrower 

 than in S. a. borealis from the Altai, and the brain-case also is not so wide. 

 The sides of the interpterygoid fossa are parallel. In the type the pigmen- 

 tation of the teeth is rather faint, and is lacking on the hypocones of the 

 upper molariform teeth and on the protocone of the third upper molar. 

 In most of the series, however, the hypocones of the first and second molars, 

 but not of the large second premolar, are tipped with pigment, and the 

 same is true of three out of four specimens of S. a. borealis. The lobes of 

 the first lower incisor are well indicated, and are essentially as in S. araneus. 



Measurements. — The type, measured by the collector: total length, 

 74 mm.; tail, 24; hind foot, 11.5. The extremes of ten other specimens 

 are: total length, 80-93 (average 86.3); tail, 24.6-33 (average 28.8) ; hind 

 foot, 11.9-13.7 (average 12.6). 



Skull: condylobasal length, 18 mm.; basal length, 15.6; palatal length, 

 7.3; greatest width outside last molars, 4.7; least interorbital width, 3.3; 

 greatest width of brain-case, 8.3; maxillary tooth-row, 7.3; mandibular 

 tooth-row, 6.8. 



Remarks. — This is a perfectly typical member of the araneus 

 group in its dental characters, but it has begun to lose the yellow 

 side-stripe and to develop a white one instead, which is particularly 

 marked in winter skins, so that, when seen from above, the white of 

 the under parts appears to extend up to the edge of the brown 

 dorsal area. The same condition is found in S. tundrensis of 

 northern Alaska, which is clearly a New World derivative of the 

 present species. It does not seem closely related to any of the 

 eastern Asiatic forms hitherto described. 



Sorex vir sp. nov. Kolyma Brown Shrew. 



Type, skin and skull, no. 15,068, M. C. Z., adult female, from Nijni 

 Kolymsk, near the mouth of the Kolyma River, northeastern Siberia, 

 collected December 19, 1911, by Johan Koren. 



