RODENTIA SCIURJNAE CYNOMYS GTJNNISONII. 335 



CYNOMYS GUNNISONII, Baird. 



Short-tailed Prairie Dog. 



Cynomys gunnisonii, BAIRD, Pr. A. N. Sc. Phil. VII, April, 1855, 334. 



WArctamys columbianus, 1 ORD, in Guthrie's Geog. 2d Am. ed. II, 1815, 292, 302. 



?? Anisonyx brachyura, l RAP. Am. Month. Mag. II, 1817, 45. 



?? Arctomys bracfiyura, 1 HARLAN, F. Amer. 1825, 304. 

 FISCHER, Synopsis, 1829, 345. 



?? Burrowing squirrel of Columbia, LEWIS and CLARKE, II, 1815, 173. 



SP. CH. Size less than that of the S. ludovicianus, general proportions similar. Ears very short ; thumb armed with a 

 well developed claw. Tail short, the vertebral portion less than one-sixth the length of the body, with the hairs, less than 

 one-fourth. Color above rather light liver brown, mixed intimately with ash, light brown, and black ; beneath pale yel 

 lowish brown. Tail white along the edges and at the tip, with a subterminal margin of black ; the hairs at the tip are 

 white to the base, with a narrow central bar of black. The black bar sometimes wanting. 



In general appearance this sphermophile approaches to the S. ludovicianus, or prairie dog, 

 although a comparison with many specimens of the latter shows constant and sufficient distinc 

 tive characters. Its size is somewhat less. 



The hody is thick and comparatively short, the head very broad. The septum of the nose 

 only is naked. The whiskers are black, and not so long as the head. The ears are very short, 

 forming only a narrow rim around the auditory aperture ; they are thickened and densely 

 covered with hair, except inside. They are somewhat larger than those of S. ludovicianus, and 

 very similar to those of S. franJclini. The feet are weaker than those of S. ludovicianus. The 

 claws are very long and slightly curved. The thumb is armed with a stout claw, (not nail,) as 

 large as the fifth claw would be with the tip broken off. The third finger is longest ; the fourth 

 a little shorter than the second. The fifth extends barely to the base of the claw of the fourth. 

 The palms are naked. The proportions of the toes are much as in S. ludovicianus, though abso 

 lutely they are decidedly smaller. The soles are naked, with a patch of long hairs in the centre. 



The tail is very short, less than that of any species known to me, the vertebrae (in No. 501) 

 being scarcely one-ninth of the length of the body. It is covered rather densely with hair, and 

 is much flattened. 



The upper portions of the body are black, pale brownish white, gray and brown intimately 

 mixed or mottled, without any appearance of spots or bars. Anteriorly these colors have less 

 black, posteriorly more grayish. The under parts are of a light brownish yellow, darker on the 

 legs, lighter under the head and on the throat. The predominance of black hairs on the crown 

 almost gives rise to a black patch, invaded, however, by brownish gray ; the eyelids are colored 

 like the belly. On the upper parts the hairs are dark lead color at the base, then ashy white 

 for most of their length, then light brown, with the tips much lighter. The soft concealed fur 

 is ashy white to the tips ; interspersed are many hairs entirely black. Anteriorly the basal lead 

 color is almost wanting, posteriorly the ashy white becomes purer and more distinct. The hairs 

 beneath are dark lead colored at the base, less distinct anteriorly. The tail, for its basal half, 

 is like the back, otherwise it shows a mixture of black and white, with a broad and uninter 

 rupted border and tip of pure white throughout, except towards the base, where this becomes 

 yellowish. The hairs at the end of the tail are pure white throughout, except a well defined 

 and narrow ring of black in the centre, for about one-eighth of an inch ; in fact, this subter 

 minal black border can be traced for nearly the whole length of the tail. 



1 Based on the description by Lewis and Clark, as mentioned below. 



