18 U.S. NATIONAL MUSEUM BULLETIN 275 



coastal plains, were, respectively: 113.7° F (108°-120° F), 62° F (53° 

 F-74° F), and 74.2 percent. The above temperatures were taken during 

 the "summer drought" on the coastal plain and probably represent 

 the highest figures that would be obtainable during the year. Those 

 from the interior were taken during the winter or low-sun period. 

 Direct comparison of the data from the coastal plain with that 

 obtained in the Fezzan and southern Cyrenaica would lack validity, 

 as the two sets of data represent, respectively, the two extremes in 

 the annual cycle of the Libyan climate. 



The above data indicate that the Saharan interior is markedly 

 more arid than the coastal region and undergoes greater temperature 

 variation for any given 24-hour period. 



Phytogeography 



General Features of the Saharan Flora 



The following information regarding the phytogeographic charac- 

 teristics of the Sahara, including Libya, has been compiled from: 

 Ozenda, "Flora du Sahara" (1958), which includes a comprehensive 

 treatment of the flora of the northern and central Sahara; Zavattari, 

 "Prodromo della Fauna della Libia" (1934), which treats briefly the 

 regional Libyan flora; and Rattray, "The Grass Cover of Libya" 

 (1960), in which Libya is divided into several regions according to the 

 dominant type of grass cover. 



According to Ozenda, the flora of North Africa, including the 

 Sahara, comprises portions of two major floral empires: the Holarctic 

 Floral Empire which includes all of Europe, North Africa (including 

 the northern Sahara), and the greater part of Asia; and the Paleo- 

 tropical Floral Empire which encompasses the central and southern 

 Sahara and the remainder of Africa. 



Coastal Libya falls within the Mediterranean Floral Region, and 

 the Saharan interior of Libya belongs to the Saharo-Sindien Floral 

 Region, which also includes northern Arabia and southern Iran, and 

 extends as far east as the Sind Desert of West Pakistan. The flora of 

 the Mediterranean Floral Region and the Saharo-Sindien Floral 

 Region, and hence that of Libya, has most of its affinities with the 

 Holarctic Floral Empire. 



The Saharo-Sindien floral element is always dominant and contains 

 three-fourths of all the plant species that occur in the Sahara. The 

 Mediterranean affinities are naturally well developed along the north- 

 ern margins of the Sahara in Libya. A Mediterranean element exists 

 even in the mountains of the Central Sahara, but these plants are 

 Mediterranean only in origin, not in their biology. 



