40 Zoology of Colorado 



Miller and Gidley recognize five superfamilies of rodents, 

 Sciuroidea, Muroidea, Dipodoidea, Bathyergoidea, and Hystri- 

 coidea.* The first includes the squirrels, pocket gophers, pocket 

 mice, kangaroo rats, and beavers; the second the mice and rats; 

 the third the jumping mice (Zapus) and many exotic genera; the 

 fourth only African animals; the fifth the porcupines, guinea pigs, 

 etc. Thus it appears that the jumping mice and kangaroo rats 

 have quite independently acquired modified hind legs for jumping, 

 as is true of several groups of insects (fleas, grasshoppers, flea- 

 beetles). The Sciuroidea of Colorado are placed in four very 

 distinct families, the Sciuridae or squirrels and their relatives, 

 Geomyidae or pocket gophers, Heteromyidae or pocket mice and 

 kangaroo rats, and the Castoridae or beavers. Miller and Gidley 

 place all our Sciuridae in a single subfamily, but on account of 

 the very different auditory ossicles, and other features, there are 

 good reasons for recognizing a subfamily Marmotinae for the 

 marmots or woodchucks, a group of animals found in the northern 

 regions of both hemispheres. Warren, in his Mammals of Colo- 

 rado, gives only one kind of woodchuck (Marmota flaviventer) as 

 inhabiting Colorado, but since then no less than four races have 

 been recognized within the State. These are M. flaviventer luteola 

 of Howell, M. /. campioni of Figgins (type from eight miles north 

 of Higho), M.f. warreni of Howell (type from Crested Butte) and 

 M. f. obscura of Howell. The luteola form is northern, extending 

 into Wyoming; warreni is western, from Garfield County to Sagu- 

 ache County; obscura is southern, being also found in New Mexico, 

 but occurs at very high alttitudes, up to 13,700 feet. The last 

 mentioned is the largest and darkest kind. The typical M. 

 flaviventer belongs to Oregon and California, and is not found in 

 Colorado. 



Our genera of Sciurinae are quite numerous, and for the most 

 part a characteristically American group. Some are arboreal, 

 others fitted for living on the ground. Perhaps the most distinc- 

 tive genus is Cynomys of Rafinesque, the prairie dogs. The name 

 means dog-mouse. Hollister revised Cynomys in 1916 (North 

 American Fauna, No. 40), recognizing four sorts in Colorado. 

 The black-tailed prairie-dog, Cynomys ludovicianus, is the common 



♦They write Sciuroidae, etc., but I have given the more usual termination for super- 

 family names. 



