RODENTS OF LIBYA 153 



that eventually drain through the escarpment into the coastal plain. 

 In these high, windy valleys vegetation is rather abundant and 

 consists largely of grasses and other herbs. 



These gerbils were never collected in large series and were usually 

 taken less frequently in traps than other species. Other species of 

 rodents occurring sympatrically with this species include Gerbillus 

 campestris, Gerbillus eatoni, Gerbillus henleyi, Gerbillus aureus, Ger- 

 billus amoenns, and Jaculus orientalis. 



The sporadic distribution of these gerbils in coastal Libya is un- 

 accountable, as suitable habitats are present throughout virtually 

 all of coastal Libya. 



This species is unknown from the coastal areas of Tripolitania and 

 the coastal plain of the Gulf of Sirte; however, more extensive col- 

 lecting in these areas will probably reveal its presence. 



Genus Pachyuromys Lataste 



Pachyuromys duprasi natronensis de Win ton 



Pachyuromys dupresi (sic) natronensis de Winton, Nov. Zool. vol. 10, p. 285, 

 1903 (Bir Victoria, on way to Wadi Natroun from the Nile, Egypt). 



General distribution of species. North Africa, including Egypt, 

 Libya, Tunisia and Algeria, and southward into Mauritania. 



Distribution in Libya. Hamadas of Tripolitania, Cyrenaica, and 

 the northern Fezzan, and interior portions of the coastal plain of the 

 Gulf of Sirte in Cyrenaica and Tripolitania. 



Specimens examined. Twenty-four, from Cyrenaica: 65 km WNW 

 El Agheila, 1 ; Wadi er Rueis, 340 km WNW Tazerbo Oasis, 1 ; from 

 Tripolitania: 20 km E Rumia, 9; 3 km W Rumia, 2; 12 km S Chicla, 

 5; 7 km S El Gheddahia, 1 ; 5 km E Sirte, 2; 55 km SW Bir Allagh, 

 1 ; 15 km WNW Marble Arch, 1 ; 5 km E Derg, 1. 



Published records in Libya. Cyrenaica: El Agheila (de Beaux, 

 1932); Zauia Mechili (de Beaux, 1938); Fezzan: Bir el Fatia (Toschi, 

 1951). 



Measurements. Averages and extremes of six adult males and the 

 measurements of two adult females from 20 kilometers east of Rumia, 

 Tripolitania, are, respectively: Total length 165.5 (158-175), 155, 

 153; length of tail 55 (51-58), 51, 52; length of hind foot 23.5 (23-24), 

 22, 22; length of ear 17.2 (17-18), 15, 15; condylobasal length of 

 skull 31.5 (30.8-32.1), 29.8, 29.7; greatest length of skull 37.7 (36.6- 

 39.2), 35.8, 34.8; greatest breadth across auditory bullae 21.7 (21.2- 

 22.3), 20.5, ?; crown length of upper molariform toothrow 4.9 (4.6-5), 

 4.7, 4.7; least interorbital breadth 6.1 (5.9-6.3), 6, 6.1 ; greatest length 

 of nasals 12.9 (12.3-14), 11.9, 11.7; length of auditory bulla 18 (17.4- 

 18.7), 16.9, 16.9; depth of auditory bulla 14.2 (13.8-14.5), 13.5, 12.8; 

 greatest breadth across zygomatic arches 19.3 (18.7-19.9), 17.9, 18.5. 



285-1.-M O— 68 11 



