76 BOTANY OF THE 
them. In the Cape de Verds, far to the south, W. African 
and W. Indian plants replace those of the Mediterranean. 
The Island of Madeira participates in the Flora of the 
W. Indies to a much greater degree than does any part of 
the adjacent continent :—that this is in a great measure due to 
the dampness of its insular climate, is clear, from the plants 
in question being almost entirely Ferns, viz.:— 
Acrostichum squamosum, Sw. 
Aspidium molle, Sw. 
Asplenium monanthemum, Sw. 
5 furcatum, Sw. 
Trichomanes radicans, Sw. 
species found nowhere on the continent of Europe, or in 
N. Africa. The presence of a plant belonging to the other- 
wise exclusively American genus, Clethra, 1s striking, be- 
cause indicating a further relationship with the Flora of 
the New World, but of a very different character from the 
above. 
The Helichrysa of Madeira are allied in rather a remarkable 
degree to the S. African species of that genus: a fact which 
reminds us that the Myrsine Africana, a Cape of Good 
Hope plant, is a native of the Azores, but of no intervening 
latitude on the West coast of Africa or the Atlantic Islands, . 
nor indeed anywhere else but Abyssinia. Though not à. 
subject falling immediately within the province of the pure 
Botanist, it may not be amiss here to state, that the four 
Island-groups in question have been conceived by my friend, 
Professor Forbes, to be the exposed remains of one continuous 
and extended tract of land, which formed the western prolon- 
gation of the European and African shores. He points to 
the specific identity of these islands and Europe, as affording 
Botanical evidence of this ingenious theory, which, however, 
he chiefly rests on geological grounds. Regarded in this 
light, the question will resolve itself, in the opinion of most 
Botanists, into one concerning the power of migration, and 
the probability of transport having taken place, to a verY 
