130 U.S. NATIONAL MUSEUM BULLETIN 275 



including near topotypes of 67. a. vivax from Goddua, Fezzan, are 

 slightly smaller in length of skull and have slightly shorter nasals 

 and anterior palatine foramina. The length of the skull of the type 

 specimen of G. garamantis, as given by Lataste (1881), is also larger 

 than typical G. a. vir.ax. Gerbils from both countries agree closely 

 in external measurements, except for the slightly longer tail in those 

 from Libya. In color, the populations are almost identical, but speci- 

 mens from Algeria have longer, more lustrous, silkier fur. This 

 character is particularly striking in the specimen from Beni Abbes. 

 The specimens from Biskra differ in having appreciably longer and 

 more inflated auditory bullae. The foregoing differences are not of 

 sufficient magnitude to distinguish species but are more typical of the 

 subtle characters used to distinguish populations at the infraspecific 

 level. Furthermore, the enlarged auditory bullae of the specimens 

 from Biskra probably represent an extension of the east-west cline 

 apparent in populations of 67. a. amoenus and 67. a. vivax to the east. 



When the Algerian populations have been studied more thoroughly 

 and topotypical material from Ouargla becomes available for com- 

 parison, these gerbils in Algeria and Libya, which are currently known 

 as 67. garamantis and 67. amoenus, respectively, probably will be 

 regarded as conspecific and differ only as subspecies. Because of 

 priority, the current 67. amoenus will become a synonym of 67. gara- 

 mantis or be relegated to subspecific rank under the latter. 



When Lataste named 67. garamantis in 1881, Dipodillus campestris 

 (= Gerbillus campestris) and Gerbillus simoni Lataste were the only 

 North African gerbils known within the dipodil group. Comparative 

 specimens were largely unavailable from Libya and Egypt, and at that 

 time, these Algerian specimens were clearly distinct from all others 

 available to him. Ellerman and Morrison-Scott (1951) included 

 67. garamantis as a subspecies of Gerbillus nanus and thus extended 

 the range of the species far westward along North Africa. These 

 Algerian populations were several thousand miles distant from the 

 nearest representatives of 67. nanus east of the Nile River. The above 

 authors offered no explanation for this great hiatus in distribution of 

 members of the same species. Setzer (1952) assigned three specimens 

 from Kom Aushim, Giza Province, Egypt, to Gerbillus nanus gara- 

 mantis but thought it unlikely that gerbils from the Nile Valley and 

 Algeria belonged to the same subspecies. Wassif (1956) referred these 

 specimens from Kom Aushim to 67. a. amoenus and suspected that 

 67. nanus did not occur in Egypt. The present study indicates that 

 67. nanus is also not present in the mammalian fauna of Libya. 



Ecological observations. These dipodils occur in virtually all 

 types of habitats in Libya. Specimens obtained at Ghat, Edri, El 

 Gatrun, Meseguin, and near Murzuch came from areas of loose sand 



