50 U.S. NATIONAL MUSEUM BULLETIN 2 75 



successive melting and accumulations of glacial ice during pluvial 

 and interpluvial periods. During these times, rodents of European 

 affinities could have easily entered North Africa by following the 

 moist habitats appearing along the then exposed continental shelves 

 or land bridges. 



The mole rat, Spalax ehrenbergi, the field mouse, Apodemus, and 

 the dormouse, Eliomys quercinus, are all clearly of European affinities 

 and probably reached North Africa (and Libya) in this manner. The 

 mole rat, Spalax, apparently migrated to North Africa following a 

 dispersal corridor along the coastal regions of the Middle Eastern 

 countries. An eastern entry of the mole rat into North Africa is sup- 

 ported by the fact that today they do not occur west of the Cyre- 

 naican coastal plain of Libya. The direction from which the dormouse, 

 Eliomys, entered North Africa is less distinct. Dormice are presently 

 irregularly distributed along the coastal and steppe regions of North 

 and Northwest Africa from Spanish Sahara to Sinai; they could have 

 entered Africa by Avay of the Iberian Peninsula (Gibraltar) or could 

 have followed the dispersal route of Spalax and entered Africa by 

 way of the eastern Mediterranean countries. Dormice, field mice 

 (Apodemus), and mole rats must have extended their ranges south- 

 ward into Africa during one of the Pleistocene pluvials, because 

 these species are not typically desert forms. 



The fat-tailed sand rat, Pachyuromys duprasi, is typically an in- 

 habitant of the well vegetated portion of the Saharan steppe. Yet, 

 in Libya, a specimen was collected from the Wadi er Rueis near the 

 Gebel el Harug el Asued, located several hundred kilometers within 

 the Saharan interior. This disjunct population of fat-tailed sand rats 

 likewise may represent a relict of the Pleistocene that moved south- 

 ward when cooler, pluvial climates prevailed in the Sahara and with 

 the return of aridity became stranded in this localized pocket of 

 suitable habitat. 



The genera Meriones, Psammomys, Jacidus, and Allactaga probably 

 entered North Africa from Asia sometime late in the Pleistocene. 

 All are typical of arid steppes or deserts and presumably evolved in 

 the great steppes of central and southwest Asia during the Tertiary. 

 The jirds (Meriones) and the jerboas (Jacubis and Allactaga) must 

 have extended their ranges southwestward from Southwest Asia 

 during a dry interpluvial period and entered North Africa at a time 

 when the Sahara was even more widespread than now. The sand rat 

 (Psammomys) , being less restricted to arid habitats, probably entered 

 North Africa along the coastal regions of the Middle East, Sinai, and 

 Egypt as they are presently defined. The genus Psammomys is today 

 largely restricted to the coastal plain and the adjoining steppe of 



