RODENTIA SACCOMYINAE DIPODOMYS ORDII. 411 



of D. montanus. Since then, however, I have been led to believe that the colors of body and 

 tail may vary more than was imagined, and I am now inclined to think that this animal is 

 really D. ordii. It is, however, still quite unique in the white tip to the short tail, and I have 

 concluded it best to publish the description prepared for it, as follows : 



SP. CH. Above, yellowish brown, mixed with a good deal of dusky ; tail rather longer than the body, with a dusky stripe 

 on its upper and under surfaces extending to the tip ; the hairs on the extreme tip, however, being white. The white stripes on 

 the sides are continued to the end of the tail ; a decided crest above at the end. 



This animal is among the largest of the genus, and in general characters occupies a position 

 intermediate between D. ordii and D. phillipii. The head is broad and the snout acute. The 

 ears are large, broad, and coated densely behind with long appressed hairs ; the antitragus not 

 much developed. The tail is longer than the body, proportionally longer than in D. ordii, and 

 thicker than usual in the genus. The hairs upon it are unusually long, elongating crest-like on 

 the terminal third, and the hairs increasing in length to the tip, where they measure an inch. 

 On the lower edge this elongation is only distinct near the tip. The fore claws are shorter than 

 usual. 



The upper parts are dusky yellowish brown, clearer on the sides ; the general tints darker 

 than in D. ordii. There is the usual light spot above the eye, on the side of the face, and 

 behind the ear, and the light line across the thigh, The hairs on the exterior face of the ear, 

 including the posterior half andinflexed portion superiorly, are dusky lead color. The tail is 

 white, with a dusky lead colored stripe on the upper and under sides from the base to the end, 

 the hairs springing from the extreme tip being white to their base ; the basal portion of the 

 hairs on the upper surface of the tail towards the tip being white also ; those beneath, princi 

 pally lead color. The lateral white stripes are continuous to the extremity. 



This species is readily distinguishable from D. ordii by the longer tail, which has the hairs on 

 the extreme tip white, not colored, and the under surface also penicillate ; the ears are dusky 

 exteriorly. The colors .above also are duskier. The tail is shorter than in any of the other 

 species described, the dusky line below extending to the very tips of the hairs. The colors 

 are generally darker than in D. phillipii, lighter than in JD. agilis. 



To sum up the whole case in a few words, therefore, I may state that, in the specimens from 

 New Mexico, there are two distinct types of coloration ; one (Dipodomys ordii) with the upper 

 parts light yellowish brown, without any indication of plumbeous ; the tail with the upper 

 surface dusky to the tip, including all that portion beyond the end of the vertebrae ; on the under 

 surface the dark stripe ceases on the terminal third or fourth of the tail, the tail being entirely 

 white except at the end. The bases of the hairs above are, however, more or less white. 



In the other section, (D. montanus,) the upper parts are more plumbeous ; the plumbeous 

 stripes on the upper and under surfaces of the tail extend to the very tip. In one specimen, (490,) 

 the hairs of the extreme tip are entirely white, in others it is entirely plumbeous, and even for 

 some distance posterior to the end of the vertebrae. Whether, however, this is any more than 

 a variation of the same species can only be settled by additional observations. 



