Vol. XXIV, pp. 61-62 March 22, 1911 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



A NEW POCKET MOUSE FROM WYOMING. 

 BY MERRITT GARY. 



Specimens of Perognathus in the Biological Survey collection 

 from Sweetwater Valley and the northern edge of the Red 

 Desert, Wyoming, represent a well marked pale race, hitherto 

 undescribed, of P. fasciatus. , This pocket mouse may be known 

 from the following characterization : 



Perognathus fasciatus Iitus subsp. nov. 



Type from Sun, Sweetwater Valley, Wyoming. No. 160,600, Q ad., 

 U. S. National Museum, Biological Survey Collection. Collected Sept. 

 18, 1909, by M. Cary. Original No. 1778. 



Range. — Lower Sweetwater Valley and adjacent parts of Red Desert, 

 Wyoming. 



General Characters. — A little smaller than P. fasciatus, about the size 

 and proportions of P. flavescens, but with slightly larger hind foot than 

 either; color extremely pale; pelage very soft. 



Color (September specimens). — Upperparts and sides palest shade of 

 cream buff, sparsely lined with black-tipped hairs, the strong olivaceous 

 tints of fasciatus entirely absent; underparts pure white; orbital ring, 

 auricular spots and lateral line pale cream buff; tail indistinctly bicolor, 

 slightly dusky above, white below; feet white. 



Skull. — As in fasciatus. 



Measurements. — Type: Total length, 128; tail vertebrae, 59; hind foot, 

 is. Que topotype: total length, 127; tail vertebrae, 57; hind foot, 18. 



Remarks. — This pocket mouse is related to P. fasciatus of the north- 

 ern Great Plains, with which it agrees closely in all respects except 

 color. The only specimens known — two from Sun and one from near the 

 old Lost Soldier Stage Station 40 miles northwest of Rawlins — were col- 

 lected on sandy sage and .[triplex flats. A September specimen from the 

 North Platte Valley at Casper is considerably paler than typical fasciatus 

 from the Yellowstone Valley, Montana, and shows an approach to litus. 



16— Proc. Biol. Soc. Wash., Vol. XXIV, 1911. (<il) 



