NIGER EXPEDITION. 127 
The evidence of this relationship is very decided, from 
the peculiarity of the genera or species giving rise to it. 
Though comparatively few in number, their characters are 
so prominent and so widely different from the Mediterranean 
plants which accompany them, that the latter, though nume- 
rically much the greatest, seem superadded, and, as it were, 
intruders on the former. 
The Canaries and Madeira, from their central position and 
various other causes, are the centre of this Botanical region, 
called by Mr. Webb the * Macaronesian," and exhibit more 
peculiarity than the Cape de Verds, (as far as they are at 
present known), or the Azores. "There can be little doubt 
Madeira was even more peculiar in its vegetation than now, 
previous to the destruction by fire of the luxuriant forests, of 
which, almost clothing the lower parts of the island, we have 
historic evidence. Not only would such a catastrophe de- 
stroy species, but their place is afterwards occupied by strong- 
 Browing imported weeds, which prevent the re-appearance of 
the native plants by monopolizing the soil. 
With very few exceptions, the Mediterranean are the ee 
only plants found in Madeira and the Canaries besides what — — 
are confined to those islands; in the Azores, on the other — — 
hand, more Northern European species are associated wit 
| them. In the Cape de Verds, far to the south, W 
. and W, Indian plants replace those of the : 
.. The Island of Madeira. participates : 
p Orders represented by closely allied, but peculiar genera: — 
: | SCROPHULARINEA. 7 2 cai 
(eol, fade) and Callianassa, Canaries) * 
RSS uq | CAMPANULACEAS. Ee = es 
ich are fuer E represented by the singular Campam 
