RODENTS OF LIBYA 111 



Measurements. The measurements of an adult male, 321822, 

 and female, 321821, from 40 kilometers, north of Sinauen, and of an 

 adult male, 321825, from 5 kilometers east of Derg are, respectively: 

 Total length 219, 215, 217; length of tail 128, 130, 130; length of hind 

 foot 30, 30, 29; length of ear 14, 14, 13; occipitonasal length of skull 

 29.3, 28, 28.7; length of tmditory bulla 10.8, 10.5, 10.5; crown length 

 of upper molariform toothrow 3.8, 3.7, 3.8; greatest breadth across 

 zygomatic arches ?, 14.6, ?; least interorbital breadth 5.7, 5.6, 6.1; 

 breadth of rostrum at level of antorbital foramina 3.3, 2.9, 3.1; 

 greatest length of nasals 10.6, 10.6, 10.6. 



Diagnosis. Upperparts lustrous, Clay Color with uniform admixture 

 of brownish hairs extending over sides of body nearly to the venter 

 where it has greater suffusion of whitish hairs; subauricular patches 

 distinct, Cinnamon-Buff and also with admixture of brownish hairs; 

 mystacial, rostral, preauricular, and circumorbital areas, postauricular 

 patch, dorsal surfaces of fore and hind feet, and entire underparts 

 white; pinna of ear almost naked, Ochraceous-Buff, and with row of 

 buffy hairs on anterior margin; vibrissae short and white with oc- 

 casional darker hairs; fore and hind feet sparsely haired, with five 

 digits, each bearing a claw; tail distinctly bicolored Cinnamon-Buff 

 dorsally, white ventrally, with prominent terminal pencil, Avellaneous 

 dorsally and white ventrally. Skull: Relatively large, molariform 

 teeth long; interorbital breadth moderately wide; nasals short, 

 auditory bullae and posterior palatine canals large ; zygomata markedly 

 fragile and convergent anteriorly; supraorbital bead prominent; 

 braincase moderately vaulted. 



Comparisons. The two specimens, 321821 and 321822, from near 

 Sinauen and the single specimen, 321825, from Derg differ from 

 topotypes of the nominate subspecies in darker color, more streaked 

 and lustrous dorsal pelage, slightly smaller overall length, slightly 

 longer ears, slightly longer skulls, longer molariform teeth, narrower 

 interorbital breadth, slightly shorter nasals, larger auditory bullae, 

 and longer posterior palatine canals. 



Compared to a single topotype (MNHN 57) of Gerbillus gerbillus 

 foleyi Heim de Balsac from Beni Abbes, western Algeria, the speci- 

 mens from Libya are similar in dorsal color, but differ in having 

 smaller hind feet and auditory bullae, narrower zygomatic breadths, 

 and slightly shorter nasals. 



For comparisons with Gerbillus gerbillus discolor and Gerbillus 

 gerbillus psammophilous , see accounts of those subspecies. 



Remarks. The specimens from near Sinauen are slightly darker 

 in dorsal color than the specimen from Derg and also have larger 

 auditory bullae, shorter posterior palatine canals, and more vaulted 



