﻿42 



NORTH AMERICAN FAUNA. 



[No. 10. 



Ill 1894 Mr. J. A. Alien recorded a large series of Sorex personatus 

 from New Brunswick as Sorex forsteri,^ tlie name first applied to tlie 

 animal by Richardson more than sixty years before. 



KEY TO THE SPECIES OF SOREX OCCURRING IN THE UNITED STATES 

 EAST. OF THE GREAT PLAINS. 



A distinct secondary cusp on the inner side of the canine and second and 



third upper incisors (subgenus Microsorex) S. lioyi 



No secondary cusp on the canine or any of the incisors except the first. 

 Feet conspicuously fringed; size large (total length usually more than 

 150 mm. ; hind foot, over 18 mm). (Subgenus Neosorex.) 



Distinctly bicolor; belly nearly white, in strong contrast with 



color of back; chin not paler than rest of ventral surface. ... S. xmlustris 

 Nearly unicolor, or with belly somewhat grayer than back; chin 



paler than rest of ventral surface. *S^. albibarhis 



Feet not fringed ; size medium or .small (total length, less than 140 mm. ; 

 hind foot never more than 16 mm). (Subgenus Sorex.) 

 Average length, over 110 mm. ; tail more than 40 mm. 



A well-defined dark dorsal area S. richardsoni 



Back not noticeably darker than sides S. fi(7n€us 



Average lengtl], under 105 mm. ; tall less than 40 mm. 



Canine normally smaller than fourth incisor, rostrum broad 

 (ratio of greatest anteorbital breadth to palatal length, 



78) - S. longirosfris 



Caniue normally equal to or larger than fourth iucisor, rostrum 

 narrow (ratio of greatest anteorbital breadth to palatal 

 length, 61 : 71) S. personatus 



Subgenus MICROSOREX Caird. 



Microaorex Baird in Coues Precursory Notes on American Insectivorous Mammals, 

 Bull. U.. S. Geol. and Geog. Surv., Ill, No. 3, 646, 1877. Tj^pe, Sorex lioyi Baird. 



Inner side of canine and second and third npper incisors with a dis- 

 tinct secondary cusp (fig. Ic); fourtli upper incisor very minute and 



FiQ. 1.— Third upper incisor (greailj- enlarged and serai-diagrammatic), a. Sorex araneus; b, S. per- 

 sonatus; c. S. hoyi. 



nearly hidden between the third incisor and canine; brain case low 

 and narrow (ratio of cranial breadth to total length of skull ranging 

 from 42 to 47); mandible short and heavy; feet never fringe^. 



1 Bull. Am. Mus. Nat. Hist., YI, p. 100, Apr. 24. 



