REGIONS AND AREAS OF DISTRIBUTION. 485 
ordinate races as wide and vague in their geographical range. 
These severally constitute the centres of differentiation or areas of 
preservation, which I shall endeavour to define as Regions of 
Composite. Besides, however, the difficulty of assigning limits 
to adjoining regions, owing to the mutual interchange of races 
across their frontiers, even the most distant regions are sometimes 
connected by races which, owing sometimes to ready colonization, 
sometimes, perhaps, to antiquity of origin, are now found to occupy 
very wide or broken and interrupted areas; and a few races may 
be said to be truly cosmopolitan, affecting no one region more 
than another. I propose, therefore, to follow up the distinction 
of regions by a sketch of their connexions and of such evidences 
as we may trace of the supposed origin of the connecting races. 
Conjectures, however, as to the original centres or birth-places of 
all these widely dispersed and interrupted races must, of course, 
be very hazardous; for if we still hold to the axiom that affinity 
means consanguinity, we must suppose some preexisting physical 
conditions and configurations of the globe very different from the 
present ones, upon the precise nature of which those geologists 
who admit them at all, seem to be by no means agreed. Into 
these supposed conditions there would be no advantage in entering 
now; I only advert to them for the purpose of explaining that, 
when I speak of ancient connexions between regions now sepa- 
rated by impassable barriers, such as tropical America and Africa, 
Mexico and the Argentine States, South Africa and Australia, &c., 
I by no means take it as decided whether that connexion was by 
contemporaneous continuity of land-elevation or climate now 
broken off, or by successive connexions with some common land 
now destroyed, or by means of transport now no longer existing, 
or by any other facilities afforded by ancient conditions of the 
globe as yet unknown to us. 
In sketching the principal regions of the globe as marked 
out more or less distinctly by the different races of Composite 
which inhabit them, I shall commence with the primary division 
into the New and the Old World, and then detail the principal 
regions in each of these great divisions. I should observe, how- 
ever, that in using the terms New and Old World rather than 
those of Western and Eastern continents adopted by Grisebach, 
it is merely because the former appear to me to be more familiar 
and more readily understood. Neither term is strictly correct ; 
for it is not intended by the words New and Old to indicate any 
