NIGER EXPEDITION. 75 
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 
historie? evidence. Not only does such a catastrophe de- 
Stroy species, but their place is afterwards occupied by strong- 
growing imported weeds, which prevent the re-appearance of 
the native plants by monopolizing the soil. 
With very few exceptions, the Mediterranean are the 
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 with 
yi^ oan tien 
Campylanthus, (Canaries and Cape de Verd Islands.) 
2. Orders represented by closely allied, but peculiar genera :— 
ScROPHULARINEJE. 
Isoplezis, (Madeira,) and Callianassa, (Canaries.) 
CAMPANULACES. 
Musschia, (Madeira,) and Canarina, (Canaries.) 
Which are further represented by the singular Campanula Vidalii in the 
Azores, and the equally distinct C. Jacobea in the Cape de Verd Islands. 
Other instances of representation by peculiar species are found in the 
Seneciones and Sonchi, and in the curious Euphorbie of the Canaries and 
the Cape de Verds, and several other genera. * 
