1911] Taylor: Mammah of the 1909 Nevada Expedition. 253 



Of the specimens taken six were males, three females. Every 

 one, as was indicated by the condition of the reproductive organs, 

 was sexually mature. All six of the males had the testes en- 

 larged, and all three of the females contained embryos. Exact 

 data follow: No. 7976, July 1, 8 embryos; no. 7979, July 23, 

 5 embryos; no. 7980, August 1, 6 embryos. The first two were 

 secured at the head of Big Creek (altitude 8000 feet) ; the last one 

 at the Duffer Peak meadow (altitude 8400 feet). Evidently the 

 time from June to August falls in the period of gestation. 



Microtus (Lagurus) intermedms, new species. 

 Intermediate Short-tailed IMeadow Mouse. 



Type.— Male, adult; no. 7973, Univ. Calif. ]\Ius. Vert. Zool.; 

 head of Big Creek (altitude 8000 feet), Pine Forest ^lountains, 

 Humboldt County, Nevada, July 1, 1909 ; C. H. Richardson, Jr., 

 and W. P. Taylor; original no. 3082. 



Diagnostic Characters. — Slightly larger than pauperrimus, 

 but much paler; smaller than curtatus. 



Status. — Upon examining the series of six specimens of 

 short-tailed Microtus taken in the Pine Forest jMountains, it was 

 immediately apparent that their characters were not exactly 

 those of any one of the three described North American species. 

 I have at hand at the present writing topotypes of these species, 

 namelj'' Microtus pallidus C. H. Merriam, Microtus curtatus 

 (Cope), and Microtus pauperrimus (Cooper). The type locali- 

 ties are respectively, of paUidus, Fort Buford, North Dakota; of 

 curtatus, Mount Magruder, Nevada; and of pauperrimus, the 

 plains of the Columbia River in Oregon. I have access to these 

 specimens through the kindness of Dr. C. Hart Merriam. 



Compared with topotypes, or near topotypes, of pauperrimus 

 (nos. 78534, 78535, Biol. Surv. Coll.) from Antelope, Oregon, 

 June 21, 1896, it is immediately apparent that our series is much 

 paler, and cannot possibly be referred to that form. Our ani- 

 mals were trapped June 25 to July 1, and, with the possible 

 exception of one specimen (no. 7972), are fully adult. There is, 

 in intermedius as compared with pauperrimus, relatively more 

 difference between the dorsal coloration and that of the sides. 



