RODENTS OF LIBYA 51 



Libya and is similarly restricted throughout its range in North Africa 

 and the Middle East. 



Recent entry of the genera Meriones, Jaculus, and Allactaga into 

 Africa is indicated by their present distributional patterns. None is 

 known from Africa south of the Sahara, and of the three genera, only 

 Jaculus occurs virtually throughout the Sahara. The four-toed jerboa, 

 Allactaga tetradactyla, is the only representative of the genus Allactaga 

 in North Africa where it is limited to the coastal fringes of northern 

 Egypt, and in Libya it occurs only as far west as the coastal plain of 

 the Gulf of Sirte. Thus, this species apparently represents a recent 

 arrival to the African rodent fauna. The more widespread distribution 

 of jerboas of the genus Jaculus in the Sahara may reflect their greater 

 ecological tolerance and may not indicate an earlier arrival into 

 North Africa. 



The genus Meriones, represented in Libya and North Africa by 

 three species, M. caudatus, M. crassus, and M. libycus, and possibly 

 by M. shawi of doubtful validity, has a peripheral distribution in 

 relation to the Sahara. Members of this genus occur in all African 

 countries bordering on the Mediterranean Sea and in the northern 

 Sudan, Mauritania, and Spanish Sahara. With the exception of 

 occasional encroachments into the northern Sahara, such as in the 

 Libyan Fezzan, members of this genus inhabit a comparatively small 

 portion of the Sahara. 



Although suitable habitats are widespread in the isolated oases 

 of southern Cyrenaica, such as Tazerbo and Cufra, jirds (Meriones) 

 are unknown from this portion of Libya. Apparently, the great 

 tracts of sand and sandy plains comprising the Sand Sea and Serir 

 of Calanscio, and farther south, the Sand Sea of Rebianna, prevent 

 the dispersal of members of this genus. 



The distribution in North Africa, and particularly Libya, of the 

 large gerbil, Gerbillus pyramidum, agrees closely with that of the 

 genus Meriones. 



The fact that these two kinds of rodents have been unable to 

 surmount these present-day physical barriers, may indicate a recent 

 entry for them into North Africa. 



In considering faunal movements between Asia and Africa during 

 the Pliocene-Quaternary period, the Nile River, because of its great 

 length, large volume, and perennial nature, cannot be overlooked as 

 a possible barrier. In modern times, the Nile River, in combination 

 with the manmade Suez Canal, acts as a serious deterrent to the 

 movements of rodents, particularly desert rodents. The movements 

 of some species are retarded and, in some cases, curtailed by the Nile. 

 The genera of North African rodents that appear to be most restricted 



