98 U.S. NATIONAL MUSEUM BULLETIN 275 



Comparisons. Only a subadult, topotypical specimen of Gerbillus 

 eatoni eatoni is available for study, and because no specimens of 

 Gerbillus eatoni injlatus of comparable age are available, valid com- 

 parison is not possible. Specimens of G. e. injlatus, however, can be 

 readily distinguished from those representing the nominate subspecies 

 from 15 kilometers west-northwest of Marble Arch, Tripolitania 

 Province, and from 10 kilometers south of Agedabia, Cyrenaica 

 Province, by their darker, more uniform dorsal color, generally 

 larger overall size, and conspicuously larger and more inflated auditory 

 bullae. Members of this subspecies also differ from those representing 

 G. e. eatoni in having much wider and less domed braincases, wider 

 and longer posterior palatine canals, relatively shorter upper molari- 

 form toothrows, more open pterygoid fossae, and relatively shorter 

 tails. 



For comparison with Gerbillus eatoni versicolor, see account of that 

 subspecies. 



Remarks. Representatives of this subspecies can be separated 

 easily from all other subspecies of G. eatoni by then- markedly larger 

 and more inflated auditory bullae and larger size of body and cranium. 



The type series was taken from a sandy depression in the hamada 

 near the brink of the coastal escarpment. In these localized depressions, 

 the substrate is composed of poorly sorted sand and gravel and 

 supports a rather uniform plant cover of juniper-like species, large 

 grasses, and smaller, woody shrubs. Burrows are usually widespread 

 throughout these areas and suggest relatively high population densi- 

 ties. Jerboas also occur in this habitat. 



Although this subspecies is known only from the type locality, its 

 range probably includes the coastal plain and littoral deserts of 

 northern Cyrenaica and those of northern Egypt as far east as the 

 Nile River Delta. 



The name injlatus refers to the pronounced inflation of the auditory 

 bullae. 



Gerbillus eatoni versicolor, new subspecies 



Holotype. Adult male, skin and skull, USNM 325298, from 2 km N 

 Coefia, Cyrenaica Province, Libya; obtained June 15, 1962, by 

 G. L. Ranck, original no. 2341. 



Specimens examined. Twenty-five, from Cyrenaica: 2 km N 

 Coefia, 16 (2 skin only); 8 km N Benghazi, 9 (1 skin only). 



Measurements. Averages and extremes of five adult males and 

 four adult females from the type locality, with the measurements of 

 the type in brackets, are, respectively: Total length 222.4 (216-236), 

 221 (205-236), [236]; length of tail 124.2 (119-134), 121.3 (114-130), 

 [134]; length of hind foot 27 (26-28), 27.3 (27-28), [28]; length of ear 

 16 (15-17), 15.8 (15-16), [15]; occipitonasal length of skull 29.5 

 (28.7-30.3), 29.2 (28.8-30), [30.3]; length of auditory bulla 10.4 



