MAMMALS SOR1CINAE SOREX TROWBRIDGII. 13 



SOREX, Linn. 



Ears large, valvular, concha directed backwards, pattly furred on both surfaces ; tail about as long as the body, (exclusive 

 of the head,) or longer, its hairs of equal length, except at the tip ; feet moderate, not fringed ; skull slender anteriorly 

 and elongated ; upper anterior incisor with a second basal hook, and a small angular process on the inner side, near the 

 point ; two anterior lateral teeth somewhat larger than the next. 



The genus Sorex is common to both the old world and the new, and embraces a large pro 

 portion of the known species. The former have all five premolars, as in most of the American, 

 and belong to the subgenus Corsira of Gray. I see no reason, however, for using either this 

 name or Amphisorex of Duvernoy, in preference to Sorex, as the genus was established by Lin 

 naeus in 1754, upon the species S. vulgaris, belonging strictly to the present group, 1 and very 

 similar in dentition to Sorex for steri. 



The genus is divisible into two sections, one with 32 teeth, the other with 30 ; this difference 

 accompanied by others hereafter to be mentioned. Most of the species belong to the group with 

 32 teeth. For the subdivisions of these sections see the list of species at the end of the article 

 on the Sub-family Soricinae, page 10. 



To the first group of the table, or those in which the third premolar is smaller than the fourth, 

 belong all the species west of the Rocky mountains. The second group, with the gradation 

 gradual, and the teeth imbricated, includes also the European members of the genus. This and 

 the third division belong to the eastern and central portions of the continent. The species with 

 30 teeth have not been found south of the parallel of northern Ohio. 



SECTION A, WITH FIVE UPPER PREMOLARS, TEETH 32. 



Ears distinct, though not projecting visibly beyond the hair, furred on both sides ; snout 

 attenuated ; tail as long as the body, (exclusive of the head,) or longer, light colored beneath ; 

 dental formula ^ -f~ E^ 4~ Z5 32 ; anterior upper incisor with a well developed basal 

 hooked process and an internal lobe, usually in contact with its opposite ; fifth lateral tooth 

 very small ; lower anterior incisor not extending backwards to the first molar, cutting edge with 

 two or three lobed dentations ; the first lateral tooth and half the second inserted above the base 

 of the anterior incisor ; teeth white, light chesnut only on the points ; skull slender ; feet 

 moderate, not fringed ; colors generally lighter beneath ; no colored points on the inside of the 

 lateral upper teeth at the base ; lower angular process of lower jaw long and slender. 



1. Third upper premolar smaller than the fourth. 

 SOREX TROWBRIDGII, Baird. 



SP. CH. Ears very large, not exceeding the long fur ; fur full, longest hairs measuring over three lines ; fore feet broad, 

 contained 1 J times in the hinder, which are barely a little more than two-thirds the length of the skull ; tail as long as the 

 body and half of the head ; third lateral incisor smaller than the fourth ; anterior upper incisor with a moderal internal lobe. 



Color above, sooty brown or black, slightly variegated with hoary ; beneath, a little paler, and very slightly different 

 from the back ; head and body, 2 inches ; tail, 2 ; hind feet, over five-tenths of an inch. 



Body slender, elongated ; snout rather broad, depressed, and pointed ; whiskers numerous, 

 moderately long, and light colored ; eara unusually large, although not longer than the fur on 



1 See Nathusius in Wiemann's Archiv, 1838, 45. 



