76 The Mammals of Colorado 
Not very much has been published about their breeding 
habits but the young are born mostly in spring and also to a 
certain extent in summer and fall and three or four form 
a litter. 
Perodipus montanus richardsoni (for Jenness Richardson). 
Richardson's Kangaroo Rat. 
Dipodops richardsoni Allen, Bull. Am. Mus. N. H., iii., p. 277 
(1891). 
Type locality. — Sources of Beaver River, in northwestern corner 
of Indian Territory (now Oklahoma). 
Measurements. — Of large series from Baca Co., Colorado Springs, 
and other parts of eastern Colorado, practically same as P. mon- 
tanus. Specimens from Salida larger, total length, 10.40 ; tail vert., 
3.95 ; hind foot, 1.6. 
Description. — (From a specimen taken at Colorado Springs 
Dec. 7): Above a rather pale buffy ochraceous, brighter than in 
P. montanus, and heavily lined with black on dorsal area ; upper tail 
stripe dusky, quite blackish toward base ; under blackish and dusky, 
not extending to pencil, and in many specimens it does not extend 
much more than half-way to the pencil. A decidedly paler animal 
than montanus. 
Distribution. — Richardson's Kangaroo Rat is reported from 
Oklahoma, western Texas, eastern New Mexico, Colorado, north- 
eastern Utah, and Wyoming. In Colorado it is found all over 
the plains region of the eastern part of the State, coming westward 
as far as the foothills, and up the Arkansas River to at least as far 
as Salida and Poncha Springs, at a little over 7,000 feet elevation. 
It is also found in northwestern Colorado. It has been taken in 
Denver, Weld, Jefferson, Adams, Cheyenne, Yuma, El Paso, 
Pueblo, Prowers, Baca, Chaffee, Routt, and Rio Blanco counties. 
Habits. — Half-grown young of this species were taken 
in Baca County about the first of May, and near Colorado 
Springs one about three fourths grown was taken the last of 
November, showing that the breeding season may extend 
over the summer and fall. A female taken April 20th 
contained three embryos. 
