1893- THE DISTRIBUTION OF BIRDS. 105 



I. The Eurasian Sub-Region — 



1. European Province — east to the river Ob. 



2. Central Siberian Province. Between the Ob and 



the Lena. 



3. West Siberian Province. From the Lena to the 



Pacific. 

 II. The Mediterraneo-Asiatic Sub-Region — 



1. Mediterranean Province. 



2. Mediterraneo-Persic Province. 



3. Mongolian Province. 



III. Mantchurian Sub-Region. 



There is also another natural sub-region, which I propose to call : — 



IV. The Himalo-Caucasian Sub-Region. 



It consists of the highest Himalayas from 8,000-10,000 feet (ex. 

 Tetraogallus), the mountains of Tibet and the Altai to the north, and 

 westwards through the mountains of Persia to the Caucasus and the 

 hill-country of Asia Minor. 



The Mediterraneo-Asiatic Sub-Region has at least three distinct 

 provinces with characteristic forms, as was shown by Mr. H. J. Elwes 

 in his celebrated essay (Q.Z.S., 1867, pp. 645-682) : — 



1. The Mediterranean Province. 



2. The Mediterraneo-Persic Province. 



3. The Mongolian Province. 



The Mantchurian Sub-Region reaching from Eastern Siberia, south 

 of the Stanovoi Mountains, west to Lake Baikal and south to the 

 Yangtze basin, appears to me to be established by statistics. It con- 

 tains a strong Indian element, with such species as Eurystomns calonyx, 

 Halcyon pileata, Hirundo tytleri, Pericrocotus, Suthora, etc., and is further 

 characterised by several eastern representative species of well-known 

 western forms, such as Trypanocorax pastinator for T. frugilegus, Colatis 

 dauricus for C. monedula, etc. 



D. — The Ethiopian Region. 



Of the Ethiopian Region it is only necessary to remark that I 

 have greatly modified my views since I proposed zoo-geographical 

 sub-regions of Africa in 1870. The great desert of the Sahara still 

 remains a blank to us and may be called 



I. — The Saharan Sub-Region, 

 but I have come to the conclusion that a second large natural sub- 

 region can be admitted which I call 



II. — The Sudanese Sub-Region. 



The number of species which are common to Senegambia and 

 to Abyssinia and Kordofan, proclaims that there must be a natural 

 zoo-geographical sub-region stretching across between these 

 two distant areas. Its northern and southern boundaries cannot 

 yet be defined, but it is a somewhat important fact that a truly 

 Sudanese form like Melierax polyzonus has been found in Mogador 



