54 U.S. NATIONAL MUSEUM BULLETIN 2 75 



Asia, it seems appropriate to depart from conventional zoogeo- 

 graphic concepts and designate this arid belt of steppe and desert 

 as a distinct zoogeographic subregion of the Palaearctic Realm. 

 The name Saharo-Sindien Faunal Region is proposed for this new 

 subregion of the Palaearctie, which coincides rather closely with the 

 Saharo-Sindien Floral Region comprising the broad belt of steppe 

 and desert vegetation occurring over this same geographic area. 



More specifically, the Saharo-Sindien Faunal Region, referred to 

 hereafter as the Saharo-Sindien Region, is delimited as: The Saharan 

 portions of North Africa comprising the region from the Mediterranean 

 coast southward to the broad belt of Saharan steppe of north-central 

 Africa; the northern and central Sahara including Egypt, Libya, 

 Tunisia, Algeria, Morocco, Spanish Morocco, and Spanish Sahara; 

 the central and southern portions of the Sahara comprising portions 

 of the Sudan, Chad, Niger, Mali, and Mauritania, and transforming 

 farther south into the broad steppe region which extends into the 

 central Sudan, southern Chad, northern Nigeria and Senegal; all of 

 Saudi Arabia except possibly the extreme southwestern tip; the 

 steppes and deserts of Sinai, Jordan, Syria, southeastern Turkey, 

 and Iraq; the dry portions of Iran which comprise many desert and 

 steppe areas, and the central plateau which includes the desolate 

 Dasht-i-lut and Dasht-i-Kavir of eastern Iran; Baluchistan in both 

 Iran and West Pakistan ; the dry areas of northwestern West Pakistan ; 

 Afghanistan, excluding the central mountain complex; the Turkmen 

 Plains, including the Kara Kum and Kyzyl Kum Deserts; and the 

 great steppe and desert region east of the Caspian Sea, comprising 

 the dry regions of the Ust Urt and the Russian provinces of Kazakh- 

 stan, Uzbekistan, and Turkmenia, 



The most striking feature of the Saharo-Sindien Region is the 

 prevailing aridity and the sparseness of the rodent fauna. This de- 

 pauperate fauna consists of only 1 1 genera, surprisingly few considering 

 the great size of the region. All of these genera are especially adapted 

 to survive under dry conditions and even during periods of pro- 

 longed drought. 



Of the 1 1 genera of rodents occurring in the Saharo-Sindien Region, 

 almost all are endemic or, at best, occur only marginally in adjacent 

 portions of Eurasia, India, or Africa. Genera most typical of the 

 Saharo-Sindien Region include Ctenodactylus, Massoutiera Lataste, 

 Allactaga, Jacidits, Calomyscus Thomas, Gerbilhos, Pachyuromys, 

 Sekeetamys, Meriones, Psammomys, And Rhombomys Wagner. The 

 genera Gerbillvs, Meriones, and Jaculns occur virtually throughout the 

 entire Saharo-Sindien Region and are the most typical groups. 

 The genera Tatera Lataste and Acomys, although widespread in the 



