300 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. i. 



inches deep, and inside the burrow twelve inches below the sur- 

 face was white with frost." (T. S.) 



FAM. HETEROMYID.E. 

 Cricetodipus richardsoni. 



Dipodops richardsoni. Allen, Bull. Am. Mus. Nat. Hist. N. 

 Y., 1891, p. 277. 



Thirty-two examples. 30 Alva, Oklahoma Territory; 2 Cool- 

 idge, Kansas. 



" Kangaroo rats, or sand rats as they are called, are perhaps 

 the most abundant small mammals found in western Oklahoma. 

 Their center of abundance seems to be along the river bottom in 

 the sand bars and small sand-hills where vegetation is very scant. 

 They are also found sparingly in the sand-hills back on the prai- 

 rie, but never away from the sand, as they delight in it, and 

 from which they appropriately derive their common name. They 

 live in colonies, and are very industrious little animals. One 

 individual digs several holes, and by trying constantly to keep 

 the sand clear of the burrows soon enlarges them to such an ex- 

 tent that many are fully six inches in diameter. This species I 

 found active in the severest winter weather, and during my stay 

 in their range, that night was an exception when they were not 

 out in the snow, either digging or searching for food. During 

 one of the severest blizzards we had early in February, I caught 

 specimens of this species in traps and saw tracks of numbers of 

 others in the snow, the temperature being then 22 below zero. 

 At this season they seemed to be feeding principally on the seeds 

 of the cockle burr and sand burr, but last August I found the 

 seeds of the prickly pear cactus formed a great percentage of their 

 food. In fact, these hardy desert plants are about the only thing 

 they have to depend on, unless the so-called "bunch grass" be 

 excepted, on the seeds of which they may also feed. That they 

 can stand thirst for a very long period I have proved by the few 

 I have kept in captivity. These little animals make very inter- 

 esting and beautiful pets, being perfectly tame even when first 

 caught. They can easily be taken in box traps during the sum- 

 mer." (T. S.) 



Perognathus (Chaetodipus), paradoxus. 



Perognathus paradoxus, Merr. N. Am. Faun, i, 1889, p. 24. 

 Twenty-one specimens, n Alva, 6 Noble, 2 White Horse 

 Springs, 2 Arnettville, Oklahoma Territory. 



