112 U.S. NATIONAL MUSEUM BULLETIN 2 75 



braincases. These differences are too slight to warrant assignment 

 of these specimens to separate subspecies, and they are here referred 

 to the same subspecies. 



Ellerman and Morrison-Scott (1951) considered G. g. latastei to be a 

 little-known and dubious form. In the present study comparative 

 specimens of G. g. latastei are not available, but Thomas and Trouessart 

 (1903), in the original description, included the following measure- 

 ments: Length of head and body, 97; length of tail, 110; length of 

 hind foot, 27.5; length of ear, 12; length of skull from the tip of the 

 nasals to the extremity of the interparietal, 31; length of nasals, 12.5; 

 interorbital breadth, 6.3; length of diastema, 8.5; length of the upper 

 molariform toothrow, 4.4. In the original description latastei was also 

 characterized as having patches above the eyes and behind the ears, 

 all underparts pure white, hairs grayish at the base, except the post- 

 auricular patches which are entirely white, and the dorsal color of the 

 tail the same color as the back and white below with a small brownish 

 pencil. According to Thomas and Trouessart, it can be distinguished 

 from all other gerbils by its brilliant color. The three specimens 

 from Tripolitania agree closely with the above color description but 

 are somewhat smaller in most cranial characters and larger in most 

 external measurements. Owing to inadequate comparative materials, 

 the assignment of these specimens to G. g. latastei is provisional and 

 based largely on geographic grounds. 



The specimens from near Sinauen were taken from a broad slope in 

 the hamada where vegetation was sparse and interspersed with small, 

 transient dunes. The habitat at Derg was similar to that at the above 

 locality, but the plant cover was more abundant and confined to mar- 

 gins of a small wadi, and the sand was more sporadic and localized. 



This subspecies probably has a much larger distribution in Libya 

 than the few specimens would indicate, and the range probably 

 includes a large portion of the Hamada el Hamra, the Hamada de 

 Tinrhert, and the inner margins of the Tripoli tanian coastal plain. 



Gerbillus gerbillus psammophilous, new subspecies 



Holotype. Adult male, skin and skull, USNM 325078, from 

 Gialo Oasis, Cyrenaica Province, Libya; obtained Mar. 16, 1962, 

 by G. L. Ranck, original no. 1790. 



Specimens examined. One hundred eighty, from Cyrenaica: 10 

 km S Agedabia, 27 (2 skin only) ; 65 km WNW El Agheila, 1 ; 5 km 

 W El Agheila, 2; Gasr es Sahabi, 12 (6 skull only); Augila, 23; Gialo 

 Oasis, 58; 150 km S Gialo, 1 ; Wadi er Rueis, 340 km WNW Tazerbo, 

 3; El Gezira, Tazerbo Oasis, 16; Tazerbo Oasis, 23; Bir bu Zarregh, 3; 

 Bir el Harasc, 9; from Tripolitania: 15 km WNW Marble Arch, 2. 



