RODENTS OF LIBYA 209 



Specimens examined. Twenty-three, from Cyrenaica: El Giof, 

 Cufra Oasis, 19; from Tripolitania: 5 km S Socna, 1; Bir Fergian, 

 10 km S Socna, 1 (skin only); from Fezzan: El Barcat, 2. 



Measurements. Averages and extremes of 7 adult males and 10 

 adult females from El Giof, Cufra Oasis, are, respectively: Total 

 length 202 (195-209), 203.1 (185-229) ; length of tail 104.3 (100-107), 

 104.3 (99-115); length of hind foot 19.4 (19-20), 19.4 (19-20) ; length 

 of ear 19.6 (19-20), 19 (19-19); greatest length of skull 29.3 (28.4- 

 30.1), 28.7 (27.3-30); condyloincisive length of skull 27.3 (26.7-28), 

 26.5 (25-27.6); crown length of upper molariform toothrow 4.2 (4.1- 

 4.3), 4.2 (4-4.5); breadth of rostrum at level of antorbital foramina 

 3.2 (3.1-3.3), 3.2 (3.1-3.3); least interorbital breadth 4.8 (4.7-5), 4.8 

 (4.6-5); greatest breadth across zygomatic arches 14.4 (14-14.9), 14 

 (13.3-14.7); median length of nasals 10.5 (10.1-10.8), 10.3 (9.7-10.6). 



Diagnosis. Upperparts ranging from Smoke Gray on scapular 

 areas and sides to Deep Grayish Olive on middorsal region and rump ; 

 pelage of rump coarse and hispid owing to individual hairs modified 

 into stiff bristles and spines; total dorsum mildly suffused with tones 

 of Light Drab; base of pinna surrounded by band of distinct buffy- 

 gray hairs; pinna large, sparsely haired, and ranging in color from 

 Deep Grayish Olive to Dark Grayish Olive; chin, mystacial, and 

 circumoral areas, forelegs, hindlegs, dorsal surfaces of fore and hind 

 feet, and entire underparts pure white; ventral surfaces of fore and 

 hind feet naked, with distinct palmar and plantar pads, and bearing 

 five digits with claws; vibrissae relatively long, fine in texture, and 

 formed largely of grayish hairs; tail fusiform, conspicuously bi- 

 colored, Clove Brown above and Deep Olive-Buff below, and composed 

 throughout its entire length of successive, imbricated segments, from 

 the bases of which arise short, stiff, white hairs. Skull: Medium in 

 size; parietals slightly expanded dorsally; anterior palatine foramina 

 long and wide; molariform teeth relatively small and toothrow short; 

 pterygoid fossae broad and long and with prominent elliptical fo- 

 ramina on laterocaudal margins; auditory bullae small and noticeably 

 inflated ventrally; pterygoid processes convergent anteriorly and 

 forming a distinct rib separating the halves of the pterygoid fossae 

 and extending to the level of the palate. 



Comparisons. From specimens representing Acomys cahirinus 

 cahirinus (Geoffroy) from various localities both east and west of the 

 Nile River, Egypt, specimens from El Giof, Cufra Oasis, differ in 

 slightly more robust skulls, particularly the rostrum and zygomata, 

 slightly wider braincases, more expanded parietals, and a larger fora- 

 men on the laterocaudal portion of the pterygoid fossa. The foramen 

 magnum, in specimens from El Giof, is more rounded dorsally and 



