242 Viiivi rsity of Califofiiia rnhUcaiiouH in Zoology). [Vol. 7 



Distribution. — This harvest mouse was most commonly 

 recorded at Quiim River Crossing (altitude 4100 feet), where 

 twenty-three of the thirty-one specimens were captured. Other 

 localities are Big Creek Ranch (4350 feet), 4; Head of Big 

 Creek (8000 feet), 1; Leonard Creek (6500 feet), 2; and Virgin 

 Valley (5000 feet), 1. 



These records of course serve to modify Allen's statement of 

 the geographical distribution of deserti (1895a, p. 127) so as to 

 include northern as well as southern Nevada. 



The vertical distribution is unusual. The collection of one 

 specimen (no. 8213, male adult) at an altitude of 8000 feet near 

 the head of Big Creek extends the range of the species to a level 

 in the mountains at which white-bark pines were growing. The 

 slope on which this animal w^as caught faces to the south and east. 

 The sagebrush is its most characteristic plant. This may be an 

 example of a tongue of Sonoran attaining to a greater altitude 

 than usual by virtue of its peculiar exposure. A number of 

 plants and mammals more or less characteristic of the Transition 

 Zone are, however, found at even lower levels on seemingly similar 

 slopes on the east side of the mountains, which would lead to 

 the conclusion that the harvest mouse had here invaded Lower 

 Transition. The range of this form of Reithrodontomijs nicga- 

 lotis deserti is, then, characteristically the great desert flat from 

 4100 to 5000 feet in altitude in the upper Sonoran Zone. In 

 smaller numbers the harvest mice invade the mountains where 

 the slope and stream conditions are favorable, possibly even into 

 Lower Transition. 



Habits. — Harvest mice were taken in the meadows of the 

 Quinn River Ranch by wild ha^^ tussocks, under sagebrush near 

 the creek at the same locality, in the wallows along Big Creek 

 at Big Creek Ranch, on sage-covered hillsides, and on rocky sage 

 flats, the two last mentioned situations being located at an alti- 

 tude of 6500 feet at Leonard Creek. They were caught at dis- 

 tances ranging from a few feet to sixty feet from the nearest 

 water. Most of the specimens caught at Quinn River Crossing, 

 where they were the most abundant mannnal, were taken not far 

 from Wheeler Creek on the sagebrush desert. Their distribution 

 is closclv limited lo the iiciiilihoflinod of sli'caiiis. 



