Vol. XXV, pp. 127-128 July 31, 1912 



PROCEEDINGS 



OF Till 



BIOLOGICAL SOCIETY OF WASHINGTON 



A NEW MEMBER OF THE PEROGNATHUS PARVUS 

 GROUP OF POCKET MICE. 



BY J. GRINNELL. 

 [i lontribution from the Museum of Vertebrate Zoology of the University of California.] 



The Perognathus parvus group of pocket mice belongs to the 

 Upper Sonoran and Transition zones in the Great Basin region 

 of the western United States and extreme southern British 

 Columbia. According to the latest reviser of the Genus Pero- 

 gnathus (Osgood, X. Amer. Fauna No. 18, 1900, pp. 34-40) 

 the southernmost record station in California for any member 

 of this group is the San Bernardino Mountains, to which local- 

 ity a species, P. alticola, is as far as known restricted. The 

 next southernmost stations for the group are in the Inyo region 

 east of the southern Sierra Nevada, the forms there represented 

 being Perognathus parvus olivaceus and P. p. magruderensis. 

 Between these two localities, as far as published records show, 

 no form of the group has been obtained. 



One of the results of the field work carried on by the Cali- 

 fornia Museum of Vertebrate Zoology during the summer of 

 1911 was the discovery in the vicinity of Walker Pass, Kern 

 County, California, of the presence of a pocket mouse of the 

 parvus group. This member proves to be distinct from both 

 olivaceus and magruderensis to the northeast, and from alticola 

 to the south. The peculiarities of this new form, described 

 below, are so great in amount as to argue against the idea that 

 the parvus group is continuously distributed from the Inyo region 

 southwest by way of the Tehachapi and Tejon mountains to the 

 San Bernardino Mountains. The existence of such divergent 

 forms as the new species here described, and alticola, point 

 rather towards wholly disconnected habitats. The scanty data 

 at hand indicates further, that the new form is restricted to the 

 25— Pkoc. Biol. Soc. Wash., Vol. XXV, 1912. (127) 



