MAMMALS OF MINNESOTA. 205 



"General Characters. Size medium, nearly equalling that of 

 Arvicola riparius (average total length of four specimens, 

 126.25mm.) Tail very short (average length in four speci- 

 mens, 23. 75 mm. from actual base, apparent length only about 

 18 mm.) with a long terminal pencil. Ears medium, thick, 

 well haired, superior border inflexed, giving them a promi- 

 nence not seen in flat ears of the same size; antitragus medium 

 (smaller than in A. oregonus), its anterior border becoming con- 

 tinuous with the anterior base of the auricle, thus forming a low 

 rim in front of the meatus as in A. oregonus and Synaptomys 

 cooper L Fur everywhere long, full and soft . 



"Color. Upper parts every where uniform pale, buffy-gray, 

 slightly grizzled by the admixture of black- tipped hairs; under 

 parts white, the plumbeous color of the base showing through 

 in places on the belly; tail more or less obscurely bi-color." 



' 'Total length (1) male, 124mm.; (2) female, 121 mm.; (3) 

 male, 133 mm.; (4) female, 127 mm. Tail (1) 25 mm.; (2) 20 

 mm.; (3) 25mm.; (4) 25 mm. Hind foot (1) 18.25 mm.; (3) 

 18.7 mm.; (4) 17.5mm." 



"Mr. Bailey states that "the pallid Arvicolas seem to be com- 

 mon at Fort Buford. They show a decided preference for the 

 north side of steep hills. I have not found them on the south, 

 southeast or southwest sides. The only reason I can suggest 

 for this distribution is that the twilight (their favorite hour) is 

 longer on the north side. The hills where I found them are 

 all steepest on the north side, which may have some effect, 

 though there seems to be no difference in the vegetation on 

 different sides." "Their food seems to consist largely of the 

 flowers of certain plants. When these plants grow near there 

 are usually pieces of stems and blossoms of Liatris graminifolia 

 and Artemisia frigida lying about, but many other plants and 

 grasses seem to be eaten. They feed largely upon the seeds 

 of Eurotia lanata. Probably the bulbs of Liatris graminifolia 

 form a pa'rt of their diet, as is the case with Arvicola austerus." 

 * 'I have caught several grasshopper mice (Onychomys leucogaster) 

 and western white-footed mice (Hesperomys leucopus sonoriensis) 

 at their holes, and think these species either drive out the Ar- 

 vicolce or else inhabit the old holes." They are found on the 

 edge of the "Bad Lands" and from the fact that they live en- 

 tirely in the hills and from their food it may be inferred that 

 their habitat is the "Bad Lands." 



