FAMILY OF POCKET RATS 



259 



vitter a fine squeak, and if held gently for a 

 while soon cease struggling and seem to lose all 

 fear. The light evidently hurts their eyes, and 

 after blinking for a while they soon close them, 

 if held quietly in the hands or placed in an 

 undisturbed position on the ground." 



The typical Great Plains Pocket Mouse is 

 sometimes called Maximilian's Pocket Mouse, 

 from the fact that it was first discovered by 

 Maximilian, Prince of W'ied, on a journey up 

 the Missouri river, and described by him in 1839. 

 One of the smaller members of the genus, it is 

 easily distinguished by the olive-gray color of its 

 upper parts. 



The smallest of the group is the Pacific or 

 Least Pocket Mouse, found on the shore of the 

 Pacific Ocean, San Diego county, California. 

 It is but little over four inches long. 



A very curious species is the Spiny Pocket 

 Mouse, a desert Mouse of southern California 

 and northern Lower California. It has spines 

 bristling on the rump, scattered on the flanks and 

 sides, and often extending to the shoulders. 



From the contents of the pouches in animals 

 that have been trapped it is found that these 

 Mice feed on seeds of all kinds. Juniper berries, 

 corn, millet, planted peas, and cantaloupe seeds 

 seem to be favorite items in the dietary of 

 several species. Bailey says : " In a number of 

 burrows I found juniper seeds, or the empty 

 shells from which the kernel had been eaten out 

 through a little hole in one end. In some cases 

 these berries must have been brought from a 

 distance of ten or twenty rods. In one den 

 under a flat rock, where three tunnels, a foot 

 to a foot and a half long, met in a nest chamber 

 the size of my fist, there was a handful of fresh 

 juniper seeds carefully cleaned of the outer 

 pulp." 



The enemies of these Mice are the usual ene- 

 mies of the Mouse kind. The skin of a Pocket 

 Mouse has been found in a burrowing owl's 

 nest : and several rattlesnakes, on dissection, 

 were found to have preyed upon other members. 

 Domestic cats often bring them in, and they are 

 often turned up by the plough. 



POCKET RAT 

 Perodipus agilis Gainbel 



Other Name. — Kangaroo Rat. 



General Description. — A thick-set rodent with very 

 long tail and hind legs, having external cheek pockets. 

 Head large and broad ; whiskers long ; eyes large ; ears 

 broad and rounded ; tail thickly clothed with short 

 hairs and terminating in a tuft; fore legs short; hind 

 legs enormous, kangaroo-like ; pelage exceedingly soft 

 and silky. A nocturnal rodent living in burrows in the 

 plains or desert areas. 



Dental Formula. — Incisors, ^^ ; Canines, 'i^; Pre- 



' I— I 0—0 



molars, -^: Molars,^^^=i6 

 0—0 'i—i 



Pelage. — Adults: Sexes identical. Seasonal varia- 

 tion inconspicuous. Above, yellowish-brown mi.xed with 

 black, the hairs slate-gray for the basal half or three- 

 quarters ; sides ochraceous-bufif ; below, clear white ; 

 spot over eye and behind ear, side of nose, and stripe 

 running across hips and along each side of the tail to 

 the end, white; a black crescent across sides of nose 

 just before eye; tail above, blackish with blackish tip, 

 paler below. Young: Quite similar to adults, but 

 colors not so contrasting. 



Measurements, — Total length, 11.3 inches; tail verte- 

 brae, 7.1 inch; hind foot, 1.6 inches; ear .5 inch. 



Range. — Middle and southern California. 



Food. — Strictly vegetarian ; seeds, grain and mis- 

 cellaneous vegetation. 



Remarks. — There are three genera, further described 

 below, containing 45 species and subspecies. The more 

 important species of each genus follow. 



Rel.\ted Species 



Gambel's Pocket Rat. — Perodipus agilis agilis 

 Gambel. Typical animal as described above. Middle 

 and southern California. 



Ord's Pocket Rat. — Perodipus ordii ordii (Wood- 

 house). Size medium; tail shorter than Gambel's 

 Pocket Rat. From Snake Plains south to New Mexico 

 and Arizona. 



Richardson Pocket Rat. — Perodipus richardsoni 

 (Allen). Larger than Ord's Pocket Rat. Ochraceous- 

 buff lined with black. Oklahoma. 



California Four-toed Pocket Rat. — Dipodoniys 

 calif amicus californicus Merriam. Size large, color 

 dark. Northwestern California. 



Desert Pocket Rat. — Dipodoniys deserti deserti 

 Stephens. Very large and pale ; total length, 13.5 

 inches. Mojave and Colorado Deserts, California. 



Spectacled Pocket Rat, — Dipodoniys speetabitis 

 speetahilis Merriam. Size very large ; ochraceous- 

 buff lined with black above, a black crescent on sides 

 and top of nose just before eyes. Texas and Arizona 

 eastward to Sierra Blanca, Texas. 



Merriam's Four-toed Pocket Rat. — Dipodomys 

 iiterriaini nwrrianii Mearns. Above gray tinged with 

 pinkish bufif; size rather large. Arizona. 



Pygmy Pocket Rat.^ Microdipodops mcgacephalus 

 niegacephalus Merriam. Size small ; tail not tufted 

 at tip ; head large ; above, yellowish-brown mixed with 

 black and olive ; total length, 6 inches ; tail vertebrae, 

 3.2 inches ; hind foot, I inch. Central Nevada. 



