Kansas Pocket Mouse 71 
Colo., May 5.): Above buffy ochraceous, mixed with "^lack, except 
on sides which are clear buffy ; under parts white ; tail bicolor, dusky 
above, white below. The large size of this species at once distin- 
guishes it from all other Colorado pocket mice. 
Distribution. — The Kansas Pocket Mouse has a wide range, as is 
shown by the fact that it is recorded from Arizona, Colorado, Kansas, 
Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Chi- 
huahua, Mexico. In Colorado it inhabits the plains region, but 
as yet we have only a few records, widely scattered, from Logan, 
Boulder, and Baca counties. But the location of these three 
counties is such as to practically cover the whole region east of the 
foothills. 
Habits. — In one respect this species sometimes differs in its 
habits from other members of the genus, and that is that very 
frequently there are no mounds of earth about their holes, 
which may go straight down into the ground out on the 
open prairie instead of being under a yucca or something of 
that sort. Bailey says that the absence of earth at these holes 
is accounted for by the fact that they are not the main en- 
trances to the burrows, and that at the main entrance there 
is always a mound, often of considerable size, all the earth 
having been brought out that way. 
Genus PERODIPUS (Grk. pera, a pouch, + di, two, + pous, 
footed, in allusion to the pouches and long hind legs). 
Perodipus Fitzinger, 5. B. Math. Nat. O. K. Akad. Wiss. Wien, 
Ivi., p. 126 (1887). Type, P. agilis. 
Rodents with elongated hind limbs and tails, the latter hairy and 
pencilled at the tip and longer than the head and body, the former 
with elongated hairy soles and 5 clawed toes, the first small but 
distinct and always reaching the end of the metatarsus of the other 
digits; cheek pouches well developed, ears moderate, and fur soft 
and velvety. 
Skull flat and depressed, characterized by the enormously en- 
larged auditory bullae which appear on the upper surface and fill 
up the two posterior comers, displacing the other bones while below 
they touch each other across the basisphenoid ; zygomatic arches 
very slender and nearly straight, posteriorly in contact with the 
bullae ; infraorbital foramen rounded and placed nearer the incisors 
on the side of the rostrum than the root of the zygoma. Dentition: 
