﻿48 



NORTH AMERICAN FAUNA. 



[No. 10. 



Subgenus SOREX Linu. 



Sorex LiunfBus, Syst. Nat., ed. X, p. 53, 1758. Type, Soi'ex araneus Linn. 



Inner side of canine and incisor without secondary cusps (figs, la, 

 lb)', fourth upper incisor well developed; brain case moderately broad 

 (ratio of cranial breadth to total length of skull, about 50); mandible 

 slender and lightly built; feet never fringed. 



The Shrews of the subgenus Sore,r occurring in eastern North Amer- 

 ica fall naturally into three groups. Two of these are found in Europe 

 also; the third appears to be peculiar to America. The first, or araneus 

 group, represented in Europe by the type of the genus, Sorex araneus, 

 and the closely related S. aljrinus, is replaced in eastern North America 

 by S. richardsoni and S.fmneus; the second, or minutns group, to which 

 belongs the American 8. personatus, has for its European member S. 

 mhiutus; the third, or longirostris group, contains the one species, 

 tSorex longirostris Bachman. The species of the araneus group are 

 characterized by their large size, strongly built skulls, and the slight 

 development of the ridge on the antero-internal edges of the cusps of 

 the unicuspidate teeth (fig. la). The Shrews of the minutus group are 

 all small, with light papery skulls, and the antero-internal ridge on the 

 cusps of the unicuspidate teetli well developed and occasionally showing 

 the first suggestion of the minute secondary cusp characteristic of the 

 subgenus Microsorex (fig. lb). Sorex longirostris, also a very small 

 animal, is distinguished from the members of the minutus group by its 

 remarkably short, broad rostrum, and by the small size of the fourth 

 incisor. This tooth in S. longirostris is smaller than the canine, while 

 m the minutus group it is as large or larger. 



1772. Sorex araneus Forster, Philos. Trans., LXII, p. 381. (Hudson Bay.) 



1829. Sorex parvus Ricliardson, Fauna Boreali-Americana, I, p. ^. Not S. ijarvus. 



Say, 1823. (No locality.) 

 1837. Sorex richardsoni Bachman, Jour. Acad. Nat. Sci. Phila., VII, Part II, p. 383, PJ. 



XXIV, fig. 5. (Northwest Territory.) 

 1857. Sorex pachyuruft Baird, Mamm. N. Am., p. 20. Not S. pachyvrus Kiister, 1835. 



(Pembina, ^feQii.) 



1890. Sorex vulgaris Dohson, Mon. InsectiVora, Part III, fasc. 1, PI. XXIII, fig. 4. 

 (Manitoba.) 



Type locality. — Unknown. 



Geographic distribution. — Boreal zone from Minnesota and Manitoba 

 west to Alberta. Limits of range not determined. 



General characters. — Size large, equaling S. araneus; back with a 

 dark median area evident at all seasons, but especiall}^ so in winter. 



Color. — In winter: Fur everywhere slaty blackish at base; back 

 with a broad, sharply defined area of very dark walnut brown extend- 

 ing from base of tail to occiput, beyond which it fades into color of 



SOREX RICHARDSONI Bachman. 



(PI. V, fig. 4 ; PI. VI, figs. 4 and 4a. ) 



