282 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. i. 



Characters. Similar in color to R. longicaudus, but larger with 

 longer tail, larger feet and the ears conspicuously colored inside 

 with orange. 



Color. Above with dorsal area blackish-brown interspersed 

 with yellow hair, sides of head, body and upper part of forelegs 

 yellowish-brown, becoming almost a golden hue above the white 

 along the flanks. Under parts white, base of hairs plumbeous. 

 Ears with bases concealed beneath tufts of yellowish-brown 

 hairs. Apical portion outside covered with blackish-brown hairs; 

 inside orange especially conspicuous on apical third. Hands and 

 hind feet grayish-white. Tail rather stout, sparsely covered with 

 hair, brownish-black above, white beneath. Whiskers long, 

 black. On the breast are three small fulvous spots, one in the 

 center, and one at side of each foreleg. 



Cranial characters. Compared with the skull of R. longicaudus, 

 that of the present species is very much larger in every way, 

 so much superior in size as to make a detailed comparison quite 

 needless. 



Skull. Brain case very broad for its length, narrowing sharply 

 anteriorly to the orbital constriction. Nasals very broad pos- 

 teriorly, the anterior end about half as wide as the basal; 

 Auditory bullae large. Zygomatic arch .swelling very little out- 

 wards. Occipital-nasal length, 21.5 mm.: least orbital con- 

 striction, 3; length of nasals, 9; width at base, 3; greatest 

 mastoid breadth, 10; zygomatic breadth, 12; length of ptery- 

 goid, 4; palate, 4; length of Hensel, 16; greatest breadth of 

 molars outside, anteriorly, 4.5. 



Measurements. Total length, 153 mm. Tail, 79. Hind foot, 

 20. Ear, 15. 



This harvest mouse bears a general resemblance to R. longi- 

 caudus from California, but is readily distinguished by the larger 

 ears and their orange or golden hue inside, by the very differ- 

 ently colored, and larger hands and feet, and the much stouter 

 tail. There is no reddish fulvous visible, as serves to designate 

 R. arizonensis as described by Dr. Allen, and the tail is very 

 distinctly, not ''indistinctly," bicolor. 



The above-mentioned species appear to be the only ones with 

 which R. chrysotis can be compared. 



