006 MR, G. BENTHAM ON COMPOSITE. 
account of the two South-African species belonging to a section 
more abundant in America than in the Old World, and indicating 
perhaps an ancient area much more extended than the present one. 
2. Separate distribution of Composite into Regions. 
Coming now to the consideration of the separate distribution 
of Composite in America and in the Old World, we may observe 
one striking difference in this respect in the two divisions of the 
globe with regard to the extratropical or subtropical races which 
form the great bulk of the order. In America the northern and 
southern tribes are the same, although in different proportions ; 
and there are a considerable number of identical genera and even 
species in the north and in the south. In the Old World, on the 
contrary, two large northern tribes (Cynaroidew and Cichoriacez) 
are absent, or very sparingly represented, in the south ; whilst the 
southern Arctotidez, as well as several subtribes of other tribes, 
are wanting in the north ; and the genera common to the Mediter- 
ranean and S.-A frican regions (excepting cosmopolitan genera) are 
very few. This great difference in the two divisions of the globe 
may be due in a great measure to the direction of the great chain 
of mountains which in Ameriea, running north and south, facili- 
tates, or has facilitated, means of intercommunication to races of 
the constitution of Composite, to which the east and west moun- 
tain-ranges, plains, and deserts of the Old World only oppose 
obstacles. In both divisions, omitting the comparatively few 
Alpine and cosmopolitan races, we have three great specially 
composite regions which may be at once centres of differentiation 
of races and areas of preservation of mixed floras, having more of 
the former character in the Old World and of the latter in Ame- 
rica. The Mediterranean, the South-African, and the Australian 
Composite are respectively far more distinct than the Mexican, 
the Chilian, and the Brazilian, which are, moreover, further con- 
nected by what may be termed a fourth intervening region, the 
Andine; whilst in the Old World the only intermediate connect- 
ing-region between the north and south is a very partial one in 
éastern Africa. I shall now, however, enter into some further de- 
tails as to each of these regions, as well as in regard to a few others 
less defined—that is to say, the United-States region in America, 
and, in the Old World, the western, or African, and eastern, oT 
Asiatic, tropical regions. I add also to the American regions the 
West-Indian insular group, as being enclosed, as it were, betwee? 
