172 Mcrriam Descriptions of Sine Xcir Mammals. 



Crania/ and Dental Character*. Skull resembling that of Arc i- 

 cola mogollonensis in general form and in the vertical expansion 

 of the middle part of the zygomatic arch and the deflection of 

 the short nasals. The incisive foramina are a little more than 1 

 times the length of the premaxillary symphesis ; the audital 

 bulUe are large and smoothly rounded ; the last upper molar has 

 two lateral closed trjangles on its outer side, and the first lower 

 molar has 3 lateral closed triangles on the inner and two on the 

 outer side as in typical My i wines, but the middle upper molar 

 has no trace of the postero-lateral loop characteristic of the 

 members of that section from the eastern part of North America. 



(Jemis Sorex. 



No shrew of the restricted genus Sorex has been heretofore 

 known from Mexico, though a single species has been described 

 by Alston from Coban, Guatemala. It is of special interest 

 therefore to record the fact that Mr. Nelson had the good fortune 

 to secure specimens of two species on the north slope of the 

 lofty Sierra de Colima, in Jalisco, neither of which appear to 

 have been described. 



One of these, which I have named Sorex oreopolus, was found in 

 Arr/cola runways in grassy places at an altitude of 3,050 meters 

 (10,000 feet) ; the other, here named Sorex samsurei, was captured 

 at the base of a rocky ledge in a sheltered canon at an altitude 

 of about 2,440 meters (8,000 feet). The latter species may be 

 readily distinguished from the former by its much longer ears 

 and tail, by the color of its under parts, and by cranial propor- 

 tions. In the relative size of the lateral unicuspidate teeth both 

 of these shrews resemble Sorex dobsoni from the Saw Tooth 

 mountains of Idaho, though the height of the teeth is much 

 less.* The first and second upper unicuspids are subequal ; the 

 third and fourth likewise are subequal and about half the size 

 of the first and second ; the fifth is in the tooth row and dis- 

 tinctly visible from the outside, but is considerably smaller in 

 x-innmtrei than in oreopoln*. 



Three specimens of S. o/r/>yM///x and two of S. 8OM98wrei were 

 obtained. They may be known from the following descriptions : 



~*See North American Fauna, No. 5, 1891, p. 33. 



