RODENTS OF LIBYA 207 



All Libyan specimens I collected were taken in the wild or feral 

 state and, except for those from the Cyrenaican coastal plain, conform 

 in the pattern of their coloration to the wild form M. m. praetextus 

 as established by Schwarz and Schwarz. The dark-bellied specimens 

 from the coastal plain clearly represent the commensal form, M. m. 

 brevirostris. These coastal specimens have shorter rostra than those 

 from other localities, which is a character used by Schwarz and 

 Schwarz to separate M. m. brevirostris from M. m. praetextus, but 

 they lack the long tail which is reputed to be a character of the 

 commensal form. Furthermore, both color types occur together on 

 the coastal plain near Tocra, and neither show commensal tendencies. 

 To me, these different color types are only color variants of the same 

 subspecies. On the coastal plain near Tocra, and doubtless in many 

 other localities in Libya, both color types (or subspecies) occur 

 together; this clearly violates the concept that "no two subspecies 

 occupy the same geographic range." For these reasons, I prefer to 

 assign all of these mice occurring in Libya to the species AIus musculus 

 and suggest that the different color types be interpreted as various 

 stages in commensalism rather than as distinct subspecies as used 

 in the context of modern taxonomists. 



Ecological observations. In Libya, house mice are widely 

 distributed and occur in a wide variety of habitats. Frequently, 

 they act as strict commensals sharing the same dwellings as the 

 local people. At some localities, they inhabit gardens and palm groves 

 of the larger villages and oases. In many areas, they exist in the wild 

 or feral state, completely divorced from the nearest influence of man. 



The largest series were taken on the coastal plain or from the larger 

 interior oases. At Brach, in the Fezzan, house mice are abundant 

 in the interior of the oasis where slightly elevated patches of Phrag- 

 mites are interspersed among areas of open water. They are common 

 inhabitants of the dense pockets of sedges and other mesophytic 

 plants that encircle the saline lakes at El Giof and El Hauuari at 

 Cufra Oasis. On the coastal plain near Tocra, Cyrenaica, a large 

 series was taken from the dense, brush-covered coastal plain near 

 the sea. In other parts of Cyrenaica, they occur in the dense, meso- 

 phytic plant cover bordering small permanent streams or inhabit 

 localized mesic pockets in the coastal escarpment. They were occa- 

 sionally trapped in the chaparral vegetation of the higher portions 

 of the Cyrenaican Plateau. 



Relatively high humidity, mesic conditions, and dense plant cover 

 are the features common to all the above habitats. Only rarely are 

 these commensal mice taken from dry situations, and they never 

 inhabit soils formed exclusively of sand. Perhaps these dry habitats 

 are marginal and the collection of house mice from them was entirely 

 fortuitous. 



