166 U.S. NATIONAL MUSEUM BULLETIN 275 



type locality, with the measurements of the type in brackets, are, 

 respectively: Total length 316.8 (302-335), 318, ?, [335]; length of 

 tail 160.8 (151-175), 166, ?, [175]; length of hind foot 38.8 (36-41), 

 39, 39, [40]; length of ear 21.3 (20-23), 21, 20, [21]; greatest length 

 of skull 42.2 (41.5-42.8), 42.1, 44.3, [42.8]; length of palate 18 (17.5- 

 18.5), 18.2, 17.8, [18.5]; length of audital portion of auditory bulla 

 16.2 (15.6-16.7), 16.4, 16.7, [16.7]; alveolar length of upper molariform 

 too throw 5.6 (5.5-5.9), 5.5, 5.9, [5.5]; least interorbital breadth 7.6 

 (7.5-7.8), 7.1, 7.6, [7.5]; length of nasals 15.9 (15.5-16.2), 15.9, 16.7, 

 [16.2]; breadth of rostrum at level of antorbital foramina 4.1 (4-4.2), 

 4.1, 4.4, [4.2]; greatest breadth across zygomatic arches 23 (22.2-23.7), 

 22.5, 22.3, [23.7]. 



Diagnosis. Upperparts rich, lustrous, normally ranging from 

 Ochraceous-Tawny to Buckthorn Brown and with moderate admixture 

 of blackish- tipped hairs; in some paler specimens, the color of the 

 dorsum approaching Cinnamon-Buff and uniformly colored through- 

 out; long, silky guard hairs projecting 8 to 10 millimeters beyond 

 the level of the underlying pelage, particularly on the rump ; sides and 

 scapular areas lightly washed with gray; distinct whitish and bufFy 

 patches present above the eyes, between the ears and the eyes, and 

 below and behind the ears; in the pale color phase, these patches 

 almost pure white and contrasting markedly with the surrounding 

 pelage; mystacial, rostral, and circumoral areas ranging from buff to 

 pure white; eye ring black; pinnae of ears long, sparsely haired, and 

 in some specimens, almost naked; prominent row of buffy hairs 

 projecting from the anterior margin of the pinna into the internal 

 surface; vibrissae long, formed largely of white hairs, and sometimes 

 extending posteriorly for 25 millimeters beyond the level of the ears; 

 dorsal surfaces of fore and hind feet pure white; palmar surfaces 

 naked; ventral surfaces of hind feet densely furred but with promi- 

 nent hairless areas occupying the proximal one-half of the plantar 

 surface; both fore and hind feet with five digits with dark-colored 

 claws; tail exceedingly long for the species, and with a conspicuous 

 black pencil extending over the distal one-third of the dorsal surface 

 and continuing onto the ventral surface for perhaps 25 millimeters; 

 tail unicolorous in the dark color phase, except for some faint 

 suffusions of black hairs dorsally; tail contrastingly bicolored in the 

 pale color phase, Cinnamon-Buff dorsally and almost pure white 

 ventrally; entire underparts usually pure white, but in some speci- 

 mens, with faint suffusion of buff. Skull: Extremely large, angular, 

 and massive; zygomata strong and robust; auditory bullae markedly 

 inflated both ventrally and laterally; lateral meatal expansions 

 strongly inflated and firmly adpressed to squamous portion of tem- 

 poral bone; suprameatal triangle small, elliptical in shape, and 



