FIELD BOOK OF MAMMALS 



Upperparts light buff faintly sprinkled with black; white 

 spots at bases of ears well developed; buffy lateral line 

 faintly developed; tail above, brownish, below, whitish; 

 underparts white. Total length, 7 inches; tail vertebrEe, 

 3.6 inches; hind foot, .88 inch. Found in "Green River 

 Valley in southwestern Wyoming, and upper part of Snake 

 River Valley, in southeastern Idaho." (Goldman) 



Mount Magruder Pocket Mouse.— Per ognathus parvus magru- 

 derensis Osgood. 

 Colored like olivaceiis but larger. Total length, 7.8 inches ; tail 

 vertebrae, 4.1 inches; hind foot, i.oinch. Found in "Upper 

 Sonoran and Transition Zones of the desert ranges of southern 

 Nevada and adjoining portion of California." (Osgood) 



Walker Pass Pocket Mouse.- — Perognathus xanthonotus 

 Grinnell. 

 Somewhat like olivaceus but smaller. Upperparts ochrace- 

 ous buff to cream buff, slightly darkened on dorsal region 

 with black-tipped hairs, sides clearer buff; ears, inside and 

 out, sparsely clothed with white hairs; white spot at base 

 of ear conspicuous ; tail pencillate, above cream buff, darker 

 toward tip, below white; feet white; underparts white. 

 Total length, 6.8 inches; tail vertebras, 3.4 inches; hind foot, 

 .9 inch. Found in the tree yucca belt, between Upper and 

 Lower Sonoran Zones, at the southern end of the Sierra 

 Nevada, Kern County, California. 



White-eared Pocket Mouse. — Perognathus alticola Rhoads. 

 Resembling olivaceus but slightly smaller. Color as in 

 olivaceus; lateral line indistinct, ears white inside and out. 

 Total length, 6.6 inches; tail vertebrse, 3.5 inches; hind foot, 

 .88 inch. Found only in San Bernardino Mountains, San 

 Bernardino County, California. 



Northwest Pocket Mouse.— Perognathus lordi lordi (Gray). 

 Resembling parvus in the gray phase; size large; tail long; 

 color dark. Upperparts pale slaty buff, with heavy mixture 

 of black; tail as in parvus; underparts buffy with white 

 spots on pectoral and inguinal regions. Total length, 7.3 

 inches; tail vertebrae, 3.9 inches; hind foot, .92 inch. Found 

 in "Upper Sonoran and Transition Zones of the plains of 

 the Columbia River, Washington, and suitable adjacent 

 territory in southern British Columbia." (Osgood) 



Columbian Pocket Mouse. — Perognathus lordi columhianus 

 (Merriam). 

 Differing from typical lordi in slight cranial characters; 

 color as in typical lordi. Total length, ^.2 inches; tail ver- 

 tebrae, 3.7 inches; hind foot, .9 inch. Found in vicinity of 

 Pasco, Franklin County, Washington. 



Formosus Group 



Long-tailed Pocket Mouse. — Perognathus formosus Merriam. 

 Size large; tail long and tufted; ears large; soles of hind feet 

 naked. Upperparts grizzled sepia; sides like back; ears 



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