42 Zoology of Colorado 



after General John C. Fremont, whose expedition obtained the 

 original specimen. A much larger squirrel, the head and body 

 about a foot long, is Sciurus aberti, after Col. J. J. Abert, who led 

 an expedition into the southwest. The Abert squirrel, found 

 principally in the foothill country, among the pines, is a very 

 handsome animal, with long tufted ears. The color is variable, 

 so that two races or varieties, mimus of Merriam and ferreus of 

 True, have been distinguished; the latter originally recorded from 

 Loveland.* Two other races have been found in the States of 

 Chihuahua and Durango, Mexico. 



The genus Citellus includes the spermophiles (the word mean- 

 ing seed-lovers) and ground squirrels, according to Warren's 

 Mammals of Colorado; but Miller and Mearns separate the 

 ground squirrels as a genus Otospermophilus of Brandt, these 

 being larger animals with longer tails. The auditory ossicles of 

 Otospermophilus strongly support its separation from typical 

 (European) Citellus; but unfortunately the American C. elegans, 

 at least, has ossicles similar to those of the ground squirrels. 

 There is thus some basis for recognizing the genus Ictidomys of 

 Allen (type C. tridecemlineatus) for the American animals. Miller 

 in his work on the Mammals of Western Europe, says "the limits 

 of the genus Citellus are not at present well understood, owing 

 chiefly to the difficulty of comparing the Old World and American 

 forms." However C. elegans, the ossicles of which were examined, 

 is placed by Elliot (1901) in the subgenus Colobotis of Brandt, 

 which was originally based on C. fulvus from southern Russia. 

 It accordingly appears that we may eventually recognize a single 

 genus, or two, or three, for the animals now called Citellus. There 

 is a good opportunity for anyone who can obtain specimens, to 

 make a careful study of the whole anatomy, and so decide the 

 matter. 



Our most familiar spermophile is the longitudinally striped 

 species, Citellus or Ictidomys tridecemlineatus. The dark stripes 

 have light spots upon them, so that the whole appearance of the 

 animal is characteristic and unique. This animal exists in Colo- 

 rado in two distinct races. The larger one, nine to nine and one- 



*Dr. Allen wrote to Mr. Warren, that he doubted the distinctness of the race mimus. 



