NO. 24 MAMMALS FROM SIBERIAN ALTAI — HOLLISTER 3 



Skull and teeth. — Skull very much larger than that of 5". a. 

 borealis; braincase even considerably larger than in S. a. tetra- 

 gonurus, broader, longer, and relatively flattened ; lambdoid crest 

 well developed in young adult. Incisors as in araneus; unicuspid 

 teeth of same relative sizes as in araneus, but much longer crowned, 

 the cones thus much wider apart, giving the appearance of wider 

 spacing. The first two upper unicuspids longer than high, the first 

 with length of crown about one and one-half times height at cone ; the 

 anterior line of profile steep ; the posterior line sharply squared, with 

 long shelving heel as long as posterior height of cusp above this shelf. 

 The highest point of cusp of this tooth is distinctly over anterior 

 third of crown. Second upper unicuspid with crown long, but con- 

 siderably shorter than in first ; third, fourth, and fifth much as in 

 araneus. Large upper premolar with hypocone obsolete ; first and 

 second upper molars with hypocones much reduced, hardly noticeable, 

 and without pigment. These teeth are in contact only on extreme 

 outer edge, with wide spaces between centers and inner corners. 

 Third upper molar with well developed pigmented protocone. Lower 

 teeth much as in tetragonurus, but smaller, the molariform teeth 

 much compressed laterally. 



Measurements of type. — Head and body, 74 millimeters ; tail 

 vertebrae, 41; hind foot, without claws, 14. Skull: (Condylobasal 

 length, estimated from broken skull, 22) ; breadth of braincase, 9.8 ; 

 depth of braincase, 5.5; length of mandible, 10.8; length of upper 

 molariform tooth row, 4.5 ; length of entire mandibular tooth row, 



8.3. 



Remarks. — In a series of ten shrews from the Altai Mountains, 

 nine of which represent the Sorex araneus borealis of Kastschenko, 

 this single specimen is conspicuous by its large size, dark color, large 

 hind foot, and peculiar dental structure. Though of the " araneus 

 group " it clearly represents a distinct species, which is readily recog- 

 nizable in the flesh from the subspecies of araneus found in the same 

 forests. The skull was broken by the trap, but the braincase is per- 

 fect and the dentition complete. 



