284 PROCEEDINGS OF THE ACADEMY OF 



f. Naturg. 1841, 45; Suppl. Schreb. iii. 1843, 612. Scliinz, Syn. 



Mamm. ii. 1845, 259. Led, Proc. Acad. Nat. Sci. Pbila. vi. 1853, 224. 



Aud. *fc Bach., Q. N. A. iii. 1854, 341 (compiled). Giebel, Saugeth. 



1855, 572 (compiled). Bd., M. K A. 1857, 421 (Chihuahua). Bd., 



U. S. Mex. Bound. Surv. ii. pt. ii. 1859, Mamm. p. Suckl., P. R. 



R. Rep. xii. pt. ii. 18G0, 101 (compiled). Gray, P. Z. S., 1868, 201. 

 Perognatus fasceatus, Lincecum, Am. Nat. vi. 1872, p. 369 (habits). 

 Prognathic faceatus, Lincecum, Am. Sportsman, Feb. 28, 1874 (habits). 



Diagn. Largest of the genus ; considerably exceeding Hespe- 

 romys leucopus, and approaching Tamias quadrivittatus in size ; 

 length four inches or more: tail less ; hind foot about one inch. 

 Tail decidedly shorter than head and body, not penicillate. Ears 

 large; antitragus distinctly lobed. Soles naked to the heels at 

 least along a median strip. Above, reddish-} r ellow, closely lined 

 with blackish; below, including fore leg all around, white ; these 

 two colors separated by a conspicuous stripe of fawn color or 

 salmon red running the whole length of the body ; tail distinctly 

 bicolor. 



Hab. United States, west of the Mississippi and east of the 

 Rocky Mountains, and northern portions of Mexico. (Originally 

 described from the mouth of the Yellowstone ; re-described from 

 Chihuahua. Specimens examined by me from Nebraska, Kansas, 

 Texas, and Chihuahua.) 



I regret that the material before me includes no specimens in 

 the flesh, since I am thereby prevented from giving the size and 

 form of the species with desirable precision ; fortunately, how- 

 ever, in this instance the characters of the species are so strongly 

 marked, that lack of elaborate details of form will result in no 

 misunderstanding. The coloration, alone distinctive, can be ac- 

 curately given from several well-prepared skins before me. 



This species, the type of the genus, exhibits very distinctly the 

 two leading features of external anatomy which distinguish Perog- 

 nathns proper from Cricetodipus ; namely, the lobe of the anti- 

 tragus and the naked strip of the sole extending quite to the heel. 

 It is much the largest species of the genus known to inhabit the 

 United States, considerably exceeding P . penicillatus (which about 

 equals Wesperomys leucopus in size), and in fact, some specimens 

 are little if any smaller than Tamias quadrivittatus. For the 

 reason above given, the dimensions cannot be stated with precision ; 

 but the length from nose to root of. tail is obviously more than 

 four inches in all but one of the specimens before me; the tail is 



