240 U.S. NATIONAL MUSEUM BULLETIN 275 



dorsum, lighter coloration of the dark portion of the pinna of the 

 tail, and much lighter, more ochraceous color of the dorsum. 



In smaller size of almost all cranial and external measurements, 

 this subspecies is readily separable from Jaculus jaculus arenaceous. 



For comparison with Jaculus jaculus collinsi, see account of that 

 subspecies. 



Remarks. Specimens were taken only from extensive areas of 

 "hamada" or pebble desert supporting a scanty vegetative cover. 

 While foraging at night, these jerboas seem to prefer the rather barren 

 areas peripheral to the oases proper. The conspicuous absence of bur- 

 rows in these areas suggests, however, that the animals actually 

 dwell and construct burrows in the sandy areas nearer the oases. 



The name cujrensis is proposed in reference to the oasis of Cufra in 

 southern Cyrenaica. 



Jaculus jaculus tripolitanicus, new subspecies 



Holotype. Adult male, skin and skull, USNM 325773, from 25 

 km N Gharian, Tripolitania Province, Libya; obtained Mar. 6, 1962, 

 by G. L. Ranck, original no. 1725. 



Specimens examined. Five, from Tripolitania: 25 km N Gharian, 

 4;40kmENE Nalut, 1. 



Measurements. The measurements of an adult female, 325771, 

 and the averages and extremes of three adult males, 325770, 325772, 

 and 325773, from the type locality, with the measurements of the 

 type in brackets, are, respectively: Total length 302, 298.3 (290-300), 

 [300]; length of tail 193, 181.7 (174-184), [184]; length of hind foot 66, 

 66.3 (61-65), [61]; length of ear 23, 21.7 (21-22), [22]; greatest length 

 of skull 36.4, 34.9 (34.9-34.9), [34.9]; condyloincisive length of skull 

 31.9, 30.4 (30.2-30.6), [30.2]; crown length of upper molariform tooth- 

 row 5.3, 5.5 (5.4-5.7), [5.7]; greatest breadth across zygomatic proc- 

 esses 22.5, 22.6 (21.4-24.1), [24.1]; least interorbital breadth 12.5, 

 12.6 (12.3-12.9), [12.6]; length of nasals 13.4, 12.4 (11.7-13), [12.5]; 

 breadth of rostrum at level of antorbital foramina 5.2, 4.8 (4.7-4.8), 

 [4.8]; greatest breadth of braincase 19.2, 18.7 (18.2-19.1), [18.9]; 

 greatest breadth across antorbital processes 23.7, 23.1 (22-23.8), 

 [23.8]. 



Diagnosis. Upperparts, subauricular region, and flanks Cinnamon- 

 Buff with strong admixture of brown-tipped hairs, more concentrated 

 on rump; lateral areas Pinkish Buff with suffusion of dark hairs; 

 overall dorsal coloration a uniform blending of light and dark hairs; 

 rostral, supra- and infraorbital, mystacial, and postauricular areas 

 Pale Pinkish Buff; pinna of ear sparsely haired with fringe of buffy 

 hairs along anteromedial margins and otherwise Clay Color basally 

 and Tawny-Olive terminally; fore and hind feet white dorsally; fore- 



