﻿Dec, 1895.] 



SOREX HOYI. 



43 



Baircl establislied tbe snbgenas Mlcrosorex iu 1877 in a paper pub- 

 lished by Dr. Cones. The characters as originally given were false, 

 since it was snpposed that Sorex hoyi, the type of the subgenus, had 

 only 30 teeth, while in reality it has 32, the number normally present 

 in the genus. Althougli the subgenus can not be distinguished by 

 the number of teeth, it is amply characterized by cranial and dental 

 peculiarities which will be more fully discussed in the description of 

 Sorex hoyi. The form of the skull, and especially of the mandible, in 

 this Shrew is so peculiar as to suggest that it may be necessary even- 

 tually to recognize Microsorex as a full genus. 



So far as known, Microsorex is peculiar to America, where it is repre- 

 sented by one species, Sorex hoyi Baird. 



SOREX HOYI Baird. 



(PI. V, figs. 6 and 7; PI, VI, figs. 10 and 10«.) 



1857. Sorex hoyi Baird, Maram. N. Am., p. 32. (Racine, Wis.) 

 1857. Sorex lltompsoni Baird, Mamm. N. Am., p. 34. (Burlington, Vt.) 

 1862. Sorex thompsoni Verrill, Proc. Bost, Soc. Nat. Hist., IX, p. 169. (Maine.) 

 1890, Sorex hoyi Dobsou, Mon. Insectivora, Part III, fasc. 1, PI. XXIII, figs. 15, 16rt. 

 (New York and Manitoba.) 



Type locality. — Racine, Wisconsin. 



Geographic distribution.— Borea} zone and adjacent part of Transi- 

 tion zone from JMiimesota to New Brunswick and Nova Scotia. 



General characters. — Sorex hoyi is the only known species of Micro- 

 sorex. It may be recognized by the subgeneric characters. 



CoZor.— Back and sides hair brown, more or less darkened with clove 

 brown on the former, and shading, without line of demarcation, into 

 the pale hair brown or silver gray of the belly. Dorsum of manus and 

 pes and ventral surface of tail pale Isabella color. Eegiou between 

 front legs usually tinged with fulvous. 



The color of the back varies slightly, being more darkened with 

 clove brown in some individuals than in others. The chest is often 

 very strongly tinged with fulvous, and at least a trace of this color is 

 present in every specimen that I have examined. 



Sknll. — The skull of Sorex hoyi (PI. VI, tigs. 10, 10a) is small, thin, and 

 pai)cry. In form it differs from that of other species of Sorex in the 

 flattened and narrowed brain case and in the short thick mandible, 

 the latter resembling that of the smaller species of Blarina. The pecu- 

 liarities in form as compared with Sorex per son atus and S. richardsoni 

 are shown in the following table of approximate cranial ratios: 





II 



Sorex 

 person- 

 atus. 



Sorex 

 richard- 

 soni. 



Eatio of crauial breadtli to total length of skull 



45 



51 



51 





28 



28 



27 





80 



70 



60 



liatio of palatal bvcadtli to cranial breadth 



60 



55 



52 



Hatio of palatal depth to cranial depth 



40 



51 



40 





49 



51 



53 



