Family SORICIDAE 



55 



teeth that are tipped with red. It has a relatively long tail, 

 which reaches nearly to the ears when laid forward along the 

 back. In winter this animal is brown on the upper parts, smoky 

 gray on the under parts; in summer it is a slightly darker 

 shade. The eyes and ears are masked or covered by short hair; 

 hence the common name of masked shrew. 



Length measurements: head and body \]/s-2]/z inches (47-63 

 mm.); tail lj4-1^4 inches (33-46 mm.); over-all 3\4,-4l4 

 inches (80-109 mm.); hind foot about \/i inch (10-13 mm.). 

 Weight: about Is ounce (4 gm.). 



The skull is slender, tear-drop shaped, and 16.5 mm. (about 

 ■Hi inch) long. The teeth are numerous (32), small, and sharp 

 pointed. On each side of the upper jaw there is one large front 

 incisor which is notched and projected forward. Behind this 

 tooth are five small teeth, called unicuspids (one-cusped teeth). 

 The fourth unicuspid is about the same size as or smaller than 

 the third unicuspid, and the fifth unicuspid is so small that it 

 may be overlooked, fig. 44^. Dental formula: I 3/1, C 1/1, 

 Pm 3/1, M 3/3. 



The masked shrew may be confused with the southeastern 

 shrew. The two are best distinguished by differences in the uni- 

 cuspids. They differ in distribution; the masked shrew has never 

 been taken in southern Illinois, and there are no authentic rec- 

 ords of the southeastern shrew from northern Illinois. 



The masked shrew may also be confused with the pigmy 

 shrew, but generally the masked shrew is larger, has a longer 



Fig. 46. — Masked shrew. 



