96 U.S. NATIONAL MUSEUM BULLETIN 2 75 



level of antorbital foramina 2.9 (2.8-3), 3 (2.9-3.2); greatest length 

 of nasals 10.6 (10.6-10.7), 10.7 (10.5-10.8). 



Diagnosis. Upper parts Sayal Brown suffused with Bister; tail 

 Cinnamon-Buff and bicolored owing to strong suffusion of brownish 

 hairs dorsally; postauricular patches prominent and white; pinna of 

 ear sparsely haired, Clay Color basally and becoming darker distally; 

 vibrissae short and formed from about equal numbers of brown and 

 white hairs; eye ring dark brown; mystacial, rostral and pectoral 

 areas, flanks and sides Cinnamon-Buff; forelegs, hindlegs, and feet 

 white dorsally, sparsely haired ventrally and each bearing five digits 

 with claws; entire underparts white. Skull: Relatively small and 

 gracile; upper molariform teeth relatively short; anterior palatine 

 foramina short and wide; posterior palatine canals relatively short; 

 auditory bullae large and markedly inflated; braincase prominently 

 arched. 



Comparisons. Members of the nominate subspecies can be dis- 

 tinguished from those representing other subspecies in Libya by 

 their smaller size and the marked doming of the braincase. For more 

 detailed comparisons with Gerbillus eatoni inflatus and Gerbillus eatoni 

 versicolor, see accounts of those subspecies. 



Remarks. Only a single, subadult topotype of G. e. eatoni is available 

 for this study. When specimens of comparable age from various locali- 

 ties along the Gulf of Sirte are compared to this topotype, they differ 

 in having lighter dorsal color, less doming of the skull, and relatively 

 smaller and less inflated auditory bullae. Even though specimens from 

 near Agedabia, Cyrenaica, do not conform precisely to the topotype 

 of G. e. eatoni, they constitute a series of sufficient size for comparisons 

 with other subspecies of G. eatoni in Libya and in the following accounts 

 will be used to represent the diagnostic characters of typical G. e. 

 eatoni. 



Specimens from near Gheminez represent the northeasternmost 

 occurrence of gerbils expressing characters typical of G. e. eatoni and, 

 in the majority of characters, are referable to the nominate subspecies, 

 but in dorsal color and length of tail, they show intergradation with 

 G. e. versicolor to the north. 



One old and aberrant male specimen, no. 325311, from Agedabia, 

 shows characters of both G. e. eatoni and G. e. versicolor. In its marked 

 divergence of the upper molariform toothrows, less domed braincase, 

 and particolored dorsal pelage, it is nearer to Gerbillus eatoni versicolor. 

 This specimen is here referred to the nominate subspecies because it 

 resembles the latter in size and degree of inflation of the auditory 

 bullae and in the majority of other cranial characters. 



Ecological observations. The habitat at Agedabia is character- 

 ized by extensive sandy plains with occasional small dunes. Vegetative 

 cover is relatively dense and composed of bushy succulent shrubs and 



