1911] Taijlor: Mammals of the 1909 Nevada Expedition. 251 



prise when working over a large rocky outcrop at an altitude of 

 only 6000 feet on Alder Creek to discover in one of our traps 

 an adult female western bushy-tailed wood rat ! The outcrop 

 was not far from the stream, and it is certain that tongues of the 

 Transition zone run down along the creek; but it was in a 

 peculiarly exposed position, and surrounded by no vegetation 

 except the almost omnipresent Artem.isia tridentata. Our desire 

 to get more of the animals was not realized until we put out a 

 line of traps in a rocky outcrop on Leonard Creek very similar 

 to the one on Alder Creek and at about the same elevation. Why 

 these wood rats should be living at such low levels is difficult 

 to explain, for many rock-piles, and of a nature entirely suitable, 

 so far as we could determine, exist at greater altitudes in the 

 mountains. There is evidently some factor not as yet under- 

 stood which influences their distribution. 



The taking of the juvenal on August 5 Avould indicate that 

 the young are born in early summer. The adult female showed 

 by the condition of the mammae, of which there were two abdom- 

 inal pairs, that she had recently suckled young. 



These animals live in crevices in the rocks, like many species 

 of round-tailed wood rats. 



Microtus mordax (C. H. IMerriam). 

 Cantankerous Meadow Mouse. 



Status. — The series of meadow mice taken by the Nevada 

 Expedition in the Pine Forest Mountains has been referred to 

 this species by Bailey. 



DiSTRiBtjTiON. — Runways which were immediately set down 

 in our note books as those of Microtus were observed at Quinn 

 River Ranch (altitude 4100 feet). However, assiduous trapping 

 failed to reveal the presence of the animals, though conditions 

 apparently could not have been more favorable. On June 15 a 

 specimen (no. 7982) was caught in a grassy location beneath 

 some willows near the stream at Big Creek Ranch (4350 feet). 

 The series was taken for the most part at the head of Big Creek 

 (8000 feet). On August 1 the species was also recorded at the 



