FIELD BOOK OF MAMMALS 



on tarsal joint; tail indistinctly bicolor, brownish dusky 

 above, white below; a clear ochraceous lateral line between 

 upper and lower parts, less distinct in worn pelages; under- 

 parts creamy white. Total length, 7.2-8.4 inches; tail ver- 

 tebrae, 3.5-4.5 inches; hind foot, .86-96 inch; ear from 

 notch (in dry skin), .86-98 inch. Found in "Southwest- 

 ern United States and northern Mexico from southern Cali- 

 fornia (east of the Sierra and San Bernardino ranges), across 

 southern Nevada, southern Utah, Arizona, to west central 

 New Mexico, and thence south. ..." (Osgood) 



Gilbert White-footed Mouse. — Peromyscus truei gilherti 

 (Allen). 

 Resembling typical truei, but darker in color, pelage not 

 quite as silky, ears smaller. Upperparts from deep och- 

 raceous to tawny, mixed with dusky (more so than in typi- 

 cal truei), ochraceous lateral line well defined; blackish 

 orbital ring sharply defined; pectoral spot may or may not 

 be present. Total length, 7.5-8.2 inches; tail vertebrae, 

 3.5-4.2 inches; hind foot, .88-.96 inch; ear from notch (in 

 dry skin), .72-.84 inch. Found in "Mountains and foot- 

 hills of the interior of California and the coast south of 

 San Francisco Bay; north to central Oregon. Chiefly 

 Upper Sonoran Zone." (Osgood) 



Martir White-footed Mouse. — Peromyscus truei martirensis 

 (Allen). 

 Practically indistinguishable in color from typical truei, 

 but tail rather longer. Total length, 8.2-8.9 inches; tail 

 vertebrce, 4.5-4.9 inches; hind foot, .96 inch; ear from notch 

 (in dry skin), .84-.92 inch. Found in "northern Lower 

 California, and northward to the San Jacinto and San 

 Bernardino mountains of southwestern California." (Os- 

 good) 



Long-nosed White-footed Mouse. — Peromyscus nasutus 

 (Allen). _ 

 Ear not quite as large as in typical truei, but nearly so ; tail 

 finely annulated. Upperparts varying in general tone from 

 grayish wood-brown to pale grayish fawn, but never show- 

 ing a decided ochraceous tinge; rest of pelage much as in 

 rowleyi. Total length, 7.2-8.4 inches; tail vertebrae, 3.6- 

 4.4 inches; hind foot, .88-.96 inch; ear from notch (in dry 

 skin), .74-.84 inch. Found in "Mountains of Colorado, 

 New Mexico, eastern Arizona, and western Texas, chiefly 

 east of the Continental Divide." (Osgood) 



Subgenus Ochrotomys 



Nuttalli Group 



Plantar tubercles six, with a seventh rudimentary tubercle; 

 abdomen suffused with color of upperparts; immature pelage 

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