INTRODUCTION. xiii 
Allusion has been made to the southward extension of elements of the Flora of the 
northern region through the great mountain-ranges to the southern limits of vegetation, 
and indications where there are remains of it on the mountains within the tropics and 
in south temperate countries. Sir Joseph Hooker's reports on the vegetation of 
Clarence Peak, Fernando Po, of the Cameroons mountains, and of Kilima-njaro are 
among the most important of the later contributions to the literature of this subject *. 
The African Region. 
The phytogeographical essays last referred to afford some most interesting details of 
the relationships and apparent migrations of the components of the vegetation of the 
great African region, which is here understood to comprise the whole of Tropical and 
South Africa, Madagascar, Mauritius, Bourbon and the contiguous groups of islets, and 
the Cape Verde Islands—Madeira and the Canaries being regarded as a province of 
the Mediterranean subregion of the Northern region. Ascension, St. Helena, Tristan 
da Cunha, and Amsterdam and St. Paul Islands, though presenting some curious 
anomalies in their vegetation, may be regarded as appanages of the African region, 
or they might be left unattached to any primary region. Excepting the Composite, 
the affinities of the flora of St. Helena are distinctly African ; and Phylica nitida, the 
only tree, or even shrub more than a trailer, in the other two groups of islands, is 
Mascarene f. Instead of arctic and temperate climates there are in this region tropical 
and temperate climates; yet botanically, as well as geographically, this is one of the 
most compact of the primary regions, and naturally divides into three subregions, 
namely:—Tropical Africa, South Africa, and Madagascar and adjacent islands. Eastern 
and Western tropical Asia should only be regarded as provinces of one Flora, as 
will presently be demonstrated. 
Besides remote connections with the Northern, American, and Australasian regions, 
there is a very intimate connection of the African with the Indian region, traceable 
from the Cape up the eastern side of the continent to Abyssinia and by way of Socotra, 
Southern Arabia, Persia, and Afghanistan to the Panjab and Gangetic plain, and less 
distinctly southward into the Deccan peninsula, with a few extensions into the Malayan 
peninsula and archipelago ; and notwithstanding the presence in the Madagascar sub- 
region of such eminently Asiatic types as Nepenthes, Lagerstremia, and a few others 
hitherto not found in continental Africa, it is evident that the interchange between 
Africa and Asia is far greater than between Madagascar and Asia, whether we con- 
sider tropical or temperate types. As might be expected, among the species common 
to India and Africa, those characteristic of a dry climate largely preponderate. On this 
* See Journ. Linn. Soc., Bot. vi. p. 1, vii. p. 171, xiv. p. 141, and xxi. p. 392. 
+ For a full account of the botany of these islands, see Botany of the ‘ Challenger’ Expedition, i. part 2, 
and Introduction. 
f 2 
