1911] Taylor: Mammals of the 1909 Nevada Expedition. 257 



Mountains, Microtus intennedius was found only at the head of 

 Big Creek, altitude 8000 feet. Thus the distribution of the 

 species so far as known is a limited area in the Transition of the 

 Pine Forest ^Mountains, Humboldt County, Nevada. 



Habits. — The area in which the intermediate short-tailed 

 meadow mice were caught is a north-facing slope at the head of 

 Big Creek. It is a dry, treeless place, covered with sagebrush. 

 The mice were caught only in the sage, on dry ground, but 

 ranged from near the stream several hundred feet up the side of 

 the ridge south of it. ^lost of those captured were secured near 

 small holes ; and on the slope itself several were caught near and 

 under rocks, under which were small burrows. On one occasion 

 two animals, both adult males, were caught, the first on June 26, 

 the second June 27, in front of the same little hole on the hill- 

 side. This may show that more than one family live in a burrow. 

 The animals were comparatively common. It is peculiar that 

 none were found at any other point in the mountains, though 

 trapping was done elsewhere on sage slopes as favorable to all 

 appearances as the one in question. There were white-bark pine 

 trees on the same side of the ridge below the level at which the 

 meadow mice were caught. 



Of the six specimens secured, four are males, two females. 

 Two of the former (nos. 7969, 7973, trapped June 26 and July 1, 

 respectively) showed signs of sexual activity, and one of the 

 latter (no. 7968), caught June 25. 1909. contained five embryos 

 almost ready to be born. Since only three of the six show any 

 indications of sexual activity, it seems that Bailey's observation 

 (1900, p. 6) that meadow mice have no definite breeding period 

 is confirmed for Microtus iutermedius, though not for Microtus 

 mordax (see p. 253). 



Status. — The form iutermedius is so well characterized as to 

 deserve specific designation. Characters of this species and those 

 previously described show all of them, however, to be rather 

 closely related. The new species is intermediate in several 

 respects between pauperrimus and curtatus. It might be argued 

 that it should be regarded as a subspecies on any other ground 

 than that of the arbitrary criterion of intergradation. But of 

 which of the older known species should it be called a subspecies ? 



