RODENTS OF LIBYA 117 



Published records in Libya. Cyrenaica: Vicinity of Benghazi 

 (Ghigi, 1920). The occurrence of this species this far north in Cy- 

 renaica is questionable. While I have not examined these specimens, 

 it seems likely that they would be representatives of Gerbillus eatoni; 

 Tripolitania: Wadi Agarib, Wadi Aggar, Ain Hammam, Ferdjan, 

 El Koshby, Linzerat, Wadi Sultan, Tamari-Ferdjan (Thomas, 1902); 

 Gargaresch, Tripoli (Andreucci, 1914); Ghadames (Perugini, 1929); 

 Giofra, Tripolitania settentrionale (Zavattari, 1937); Fezzan: God- 

 dua, Sebha, Umm el Abid, Zeigen (Thomas, 1902) ; Murzuch 

 (Andreucci, 1914); Sciati, Hofra (Zavattari, 1937). 



Comparisons. From Gerbillus aureus, which it somewhat resembles, 

 this species can be distinguished by its larger skull and body, longer 

 and more tufted tail, generally lighter color, longer and narrower 

 posterior palatine canals, and relatively narrower anterior palatine 

 foramina. 



This species can be distinguished from Gerbillus eatoni by its 

 markedly larger overall size (occipitonasal length usually more than 

 30 mm), relatively smaller and less inflated auditory bullae, larger 

 molariform teeth, and less domed, almost flattened braincase. 



This species is markedly larger in all respects than Gerbillus gerbillus 

 and has relatively larger molariform teeth, less inflated auditory 

 bullae, and less orange color in the dorsal pelage. 



Gerbillus pyramidum closely resembles Gerbillus perpallidus Setzer 

 from Egypt but can be distinguished by its darker color, markedly 

 larger skull, less inflated auditory bullae, more open pterygoid fossae, 

 longer anterior palatine foramina, and much more conspicuous supra- 

 orbital beads. The foregoing characters were used by Setzer (1958 

 p. 221) to separate these two species and I concur. 



Remarks. These gerbils are widely distributed throughout North 

 Africa from the Red Sea to the Atlas Mountains and occur virtually 

 throughout the Sahara; however, there is a conspicuous hiatus in 

 their distribution in western Egypt and eastern Libya. In Libya, 

 the oases of Gialo, Giarabub, Tazerbo, and Cufra, and in Egypt, Siwa 

 Oasis and the low-lying areas of the Qattara Depression contain 

 abundant suitable habitat for them, but as yet, no specimens are 

 known from these areas. Apparently, members of this species are 

 unable to circumvent the barriers imposed by the Cyrenaican Plateau 

 and the northern part of the Libyan Desert and have been unable to 

 extend their range into these parts of Libya and Egypt. In Libya, the 

 Serir of Calanscio and the Sand Sea of Calanscio doubtless serve to 

 further isolate the oases in southern Cyrenaica. 



This species occurs abundantly throughout western Libya in the 

 provinces of Tripolitania and Fezzan. Presently, these populations 

 in Libya are linked to those of the Nile Valley in Egypt by a series 



