MAMMAI.B. 59 



tured, but tli(\y soon became quiet and gentle. They would some- 

 times try to nip any fingers, but wlieu ])roper care was tak'en they 

 would let nio tal<e them in my hands, and would m;dve little effort 

 to escape. 



They are prolific Ijrceders, and tlie four to eight young in a, litter 

 are brought forth in the warm soft nests in dry and secluded cavities 

 underground, among rocks, hollow trees or logs, in boxes or crevices, 

 or in corners of buildings. They quickly mature and are soon run- 

 ning about in the blue-gi'ay coats which are worn through most of the 

 fii'st year. Several litters are raised each season, and the increase 

 is so rapid that any safe retreat like a vacant building is soon over- 

 run hy them. Outdoors the little owls, weasels, coyotes, and foxes 

 ])ick them up so rapidly that their abundance is well checked, and 

 when (he breeding season is over their numbers steadily decrease 

 imtil the next spring. 



They do not hibernate or become noticeably fat, but during the 

 autumn they store np considerable quantities of seeds, grain, and 

 nutlets for winter use. Buried under the deep snows of winter 

 they live safely and in comparative comfort and luxury next to the 

 ground in the tunnels which they make under the snow. They 

 also come to the surface and run over the soft snow, and lines of 

 delicate tracks may be traced in winter from one log to another, from 

 tree to tree, or from roclv pile to cliff, and thus some clue to their 

 winter habits is obtained. They climb trees readily and often oc- 

 cupy hollow trunks or even old woodpecker holes in stumps and trees. 



Mountain Lemming Mouse: Plienafomys orophUiis ^lerriam. — 

 These rare little lemming mice somewhat resemble tfie meadow mice, 

 but differ radically from them in having molar teeth with well- 

 developed, roots and different t,ype of enamel pattern. In external 

 characters they may be distinguished by their small size, light gray 

 color, and by the tail, wdiich is slender and does not noticeably taper. 

 An adult male collected on the Swiftcurrent Ri'i'er below McDermott 

 Lake measured, in millimeters: Total length, 122; tail, 30; hind foot, 

 18. Their measurements serve to distinguish them from almost any 

 of the other little rodents except the red-backed mouse, from wdiich 

 they differ strikingly in color. 



In the spring of 1895 Howell and I collected a dozen specimens 

 of these little mice at St. Mary Lake, one at Midvale, and one at 

 Summit; in August, 1917, T caught one in the open valley just 

 below McDermott Lake; and in April, 1918, I found one dead in the 

 trail near Kintla Lake. These records would indicate that lemming- 

 mice are unusually common in the Glacier Park region, and may 

 be found anywdiere along the lower slopes of the park or in the 

 open Hudsonian Zone area near timberline. Most of the specimens 



