MAMMALS OF MINNESOTA. 



211 



in size from the middle to the apex. The vibrissse are unusu- 

 ally fine and long, reaching beyond the apex of the ear, and 

 are of uncertain color, really black, but so polished as to appear 

 partly white. The sole is very densely covered with fine close 

 hairs, and there are but four tubercles. The ears vary in length, 

 but seem to be intermediate between the varieties above men- 

 tioned. 



0. pallidus burrows on the sandy prairies and seems to be 

 largely diurnal in habit. We know little regarding its habits, 

 but, inasmuch as its stomach was found filled with the remains 

 of grass-hoppers and other insects, we are justified in claiming 

 that the suggestion of a largely insectivorous diet offered by 

 the dentition is borne out by actual observation. 



The coloration must be influenced by the constant exposure 

 which a chase of diurnal insects makes necessary upon the 

 open plains; and the short and nearly naked tail are suggestive 

 of the fossorial habits. 



The following table gives all the details at command con- 

 cerning the proportions; and as all the measurements were 

 made with great care upon recently killed specimens, may be 

 trusted as thoroughly reliable.* 



GENUS FIBER, CUVIER. 

 Fiber zibethicus (L.) Cuv. 



MUSKRAT. 



Figs. 12 and 13. 



The muskrat is the largest of the mice and is typically arvi- 

 coline, differing chiefly in those modifications correlated with 

 its aquatic habits. 



The dentition is moderately individualized. The upper in- 

 cisors are semicircular with plane outer surface. The first 



*It should be said that Dr. Merriam. who has examined the types of this species in 

 the National Museum, considers the present variety identical with the type. In 

 this case the published descriptions obviously require revision. 



