100 U.S. NATIONAL MUSEUM BULLETIN 275 



is slightly smaller in overall size, has noticeably shorter and much less 

 ventrally inflated auditory bullae, smaller and more gracile skull, 

 larger upper molariform teeth which form straight toothrows rather 

 than being bowed laterally, narrower and smaller braincase, slightly 

 shorter nasals, paler, more uniform dorsal coloration (Cinnamon as 

 opposed to Sayal Brown), and less prominent subauricular patches. 



Remarks. Members of this subspecies can be distinguished from 

 other subspecies of G. eatoni in Libya by their particolored dorsal 

 pelage, more parallel upper molariform toothrows, and conspicuously 

 smaller and less inflated auditory bullae. 



Specimens from 8 kilometers north of Benghazi are similar to G. e. 

 inflatus in more uniform color of dorsum and general body size, but 

 resemble the nominate subspecies in having larger and more domed 

 braincases and more lateral bowing of the upper molariform teeth. In 

 the majority of characters, however, they are closer to G. e. versicolor 

 to which they are here referred. A small series from Gheminez, al- 

 though similar in color to G. e. versicolor, is clearly referable to the 

 nominate subspecies in all morphological characters. 



The type localities of G. e. versicolor and G. e. inflatus are, geo- 

 graphically, not too distant, but the Gebel Achdar and the massif of 

 the Cyrenaican Plateau are interposed between them and provide 

 unsuitable habitat for members of this species. Little suitable habitat 

 exists along the coastal plain owing to the encroachment of the coastal 

 escarpment. In the past, gene exchange between these two populations 

 probably has been of rare occurrence, and the two populations have 

 undergone significant morphological divergence. 



The type series was collected from an area of large, sparsely vege- 

 tated coastal dunes lying between the sea and the coastal plain. It is 

 doubtful if these gerbils are entirely limited to this type of habitat. 

 The gerbils from near Benghazi occupied the rather densely vegetated 

 coastal plain where the substrate was claylike, and sandy areas or 

 dunes were entirely lacking. These gerbils probably are not limited to 

 a particular type of substrate and occur throughout the coastal plain 

 where a wide variety of soil conditions exist. 



The name "versicolor," from the Latin meaning variegated or of 

 different colors, refers to the particolored dorsal pelage. 



Gerbillus gerbillus (Olivier) 



Dipus gerbillus Olivier, Bull. Sci. Phil. Paris, vol. 2, p. 121, 1801 (Giza Province, 

 Egypt). 



General distribution of species. Israel, Sinai, Egypt, Sudan, 

 Uganda, and North Africa south through the Sahara including parts 

 of Niger, Mauritania, Chad, and Mali. 



Distribution in Libya. Almost ubiquitous throughout the coastal 

 and interior areas of Cyrenaica, Tripolitania, and the Fezzan. 



