RODENTS OF LIBYA 191 



covering of hairs; all five digits well defined, sparsely haired, and all 

 with functional claws; entire underparts strongly suffused with 

 colors varying from Warm Buff and Ochraceous-Buff to Antimony 

 Yellow; in all specimens an irregular whitish patch is present in the 

 pectoral region; tail relatively short and same color as the dorsum 

 except for some faint admixtures of brownish-colored hairs dorsally; 

 a prominent pencil, varying in color from Cinnamon-Brown to Prout's 

 Brown, occupying the distal one-fourth of the dorsal and ventral 

 surfaces. Skull: Size relatively small for the genus but markedly 

 angular and robust; zygomata extremely strong and heavy, and in 

 older specimens, markedly bowed posteriorly; rostrum wide and 

 heavy; anterior palatine foramina relatively short and broad; posterior 

 palatine canals indistinct; molariform teeth heavy, grinding surfaces 

 usually evenly worn; pterygoid processes heavy, with distinctly 

 knobbed hamulae; auditory bulla small, not markedly inflated 

 ventrally, but with greatly expanded meatal process, which almost 

 touches squamous portion of temporal bone; suprameatal triangle 

 conspicuous, usually completely enclosed by enveloping processes of 

 temporal and supraoccipital bones; parietals with prominent lateral 

 ridges extending from lambdoidal ridge to postorbital processes of 

 frontal bone. 



Comparisons. The specimens from near Tobruch and Bardia, 

 Cyrenaica, differ from representatives of Psammomys obesus nicolli 

 Thomas from the Nile Delta and from those of Psammomys obesus 

 terraesanctae Thomas from Palestine in being markedly smaller in all 

 measurements. 



For comparisons of these specimens from Tobruch and Bardia with 

 representatives of P. o. tripolitanus , see account of that subspecies. 



Remarks. The specimens from Tobruch and Bardia are clearly 

 referable to Psammomys obesus obesus. Except for their more brilliant 

 yellowish-orange dorsal color and more worn-looking dorsal pelage, 

 they are almost indistinguishable from specimens representing P. o. 

 obesus from Salum, El Alamein, and other coastal localities to the east. 

 These differences in color are well within the expected range of indi- 

 vidual variation within a given population. 



Setzer (1957) assigned specimens of P. obesus from El Alamein, 

 Western Desert Governorate, Egypt, to P. o. tripolitanus. In a later 

 paper, Setzer (1963) regarded these specimens from western Egypt as 

 intergrades between /'. o. tripolitanus and P. o. obesus but more closely 

 related to the latter subspecies. The specimens from Tobruch and 

 Bardia, Cyrenaica, in their slightly smaller size also suggest inter- 

 gradation with P. o. tripolitanus. It is doubtful that genetic exchange 

 is common between populations of P. o. tripolitanus and P. o. obesus 

 because of the reduction or absence of coastal plain in many parts of 

 northern Cyrenaica. 



