THE FAMILY OF POCKET RATS 



{HeteromyidcB) 



family they 



OCKET Rats are placed in a separate family because of well-defined variations- 

 from other Rats, the chief difference being indicated by the name. This is 

 an interesting group of small rodents characterized, like the Pocket Gophers, 

 by cheek pouches which are used for carrying food. They are the only North 

 American animals, excepting the Gophers a«d-the^Tnping Mice, which have 

 these pockets. They include the Pocket Mice, which are usually plains-loving 

 animals, and the Pocket, or Kangaroo Rats, characterized by enormously 

 developed hind legs. These rodents have narrow incisor teeth, rootless molars, 

 and very large mastoids. Their hind feet are long, and they have either four 

 or five toes. The pelage is generally soft, but in a few species the finer hairs 

 are mixed with spiny bristles. Although a numerous and widely scattered 



are not popularly known, or even distinguished from common forms. 



POCKET MOUSE 

 Perognathus fasciatus IVied 



General Description. — A small Mouse with a large 

 head, external cheek pouches, and rather a long tail. 

 Head broad ; eyes fairly large ; ears medium size ; hind 

 legs elongate; tail well-haired and with a tuft of longer 

 hair at the tip ; pelage rather long, soft and glossy. 

 Strictly nocturnal, an inhabitant of the open plains. 



Dental Formula. — Incisors, 



; Canines, 



Pre- 



molars, - — 5 ; Molars, — ~=2o 



Pelage. — Adults : Sexes identical. Seasonal varia- 

 tion slight, .'Vbove, olive-gray tinged with pale fulvous 

 and lined with black ; pale fulvous lateral strjpe ; feet 

 and underparts white ; two light yellow patches on ears 

 and a larger patch behind ears ; tail paler below than 

 above. Young: Lacking the yellow and black of the 

 adult pelage. 



Measurements. — Total length, 5.5 inches ; tail verte- 

 brae, 2.5 inches ; hind foot, .7 inch. 



Range. — Plains of eastern Montana and Wyoming, 

 eastward into North and South Dakota. 



Food. — Seeds, grain and other vegetable matter. 



Remarks. — Considerable variation is found in color, 



■ size and character of pelage, some of the Pocket Mice 



having well developed spines among the softer hairs of 



the back. There are some 50 species and subspecies 



ranging north of the Rio Grande. 



Rel.-\ted Species 

 Great Plains Pocket Vioust.— Perognathus fasciatus 



fasciatus Wied. Typical animal of the above descrip- 

 tion. Montana, Wyoming, North and South Dakota. 



Yellow Pocket Mouse. — Perognathus flavcscens 

 flavcsccns (Merriam). Pale yellowish-brown lined with 

 blackish above. Plains of South Dakota, Nebraska and 

 Kansas, west to base of Rocky Mountains, and south 

 to Te.xas, 



Panamint Pocket Mouse. — Perognathus panamin- 

 tinus t<anamintinus (Merriam). Total length. 6 inches; 

 tail longer than head and body ; ochraceous to grayish- 

 bufT above. Panamint Mountains, California, eastward 

 through southern Nevada to St. George, Utah. 



Pacific, or Least Pocket Mouse. — Perognathus 

 pacifieus Mearns. Smallest of Pocket Mice and one of 

 the smallest mammals known ; total length, 4.3 inches ; 

 above ochraceous buff thickly mi.xed with black. San 

 Diego County, California. 



Northwest Pocket Mouse. — Perognathus lordi 

 lordi (Gray). Large; tail longer than head and body; 

 slaty-buff strongly mixed with black. Plains of Colum- 

 bia River, Washington, and southern British Columbia. 



Hispid Pocket Mouse. — Perognathus hispidus his- 

 pidus Baird. Size large; brownish-black and cinna- 

 mon : pelage harsh. Texas north to Oklahoma. 



Spiny Pocket Mouse. — Perognathus spinatus spina- 

 tus Merriam. Size medium ; drab-gray lined with 

 black; spines on rump. Desert region of southern 

 California. 



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