140 The Flora and Fauna of the Florida Keys. [March, 
South Florida, the West Indies, and Mexico, to which I refer 
the reader. I would only state that the anomaly noticed by 
Mr. Brendel in the number of species common to South Florida 
and Mexico being so much smaller than those common to the 
former and the West Indies can hardly be explained by a former 
connection of the land as he seems to imply. The distribution 
of animals, as we shall see, would not bear out this theory. 
No botanist, as far as I can find, has made a discrimination be- 
tween the flora of the keys proper and that of the mainland of 
South Florida; it would no doubt show that some of the few 
plants common to Northern and Southern Florida do not extend 
to the islands; the pine is a conspicuous example, its growth 
being apparently incompatible with pure calcareous soil; the 
Pine Keys, back of the main range, are the only ones bearing a 
growth of pines, and they have silicious sand, as I was informed 
by Professor Agassiz. I have often regretted not having visited 
them. Seen from the middle of Key Biscayne Bay the differ- 
ence between the mainland and the keys is quite conspicuous. — 
The border of mangroves is of course the same on both sides, but 
above it on the former the horizon is closed by the pine forest 50 
characteristic of the shores of the Southern States, while on the 
latter the larger trees are fig-trees of two or three species, the 
quassia (Simaruba), the torchwood (Bursera), the mahogany, 
and a few others, interspersed with a dense shrubbery, in which 
several species of Hugenia are perhaps the most common and 
characteristic. Near the water the Coccoloba, or sea-grape, forms 
conspicuous groups, and on muddy shores the mangrove and the 
Avicennia, called locally the black mangrove, are always ready 
to consolidate the new-made land, the former by its air roots a 
numerous floating fruits, the latter by its creeping roots. 
eee 
sandy places the palmetto seems to monopolize the ground, but — ; 
never rises to more than ten or fifteen feet. 
The tree vegetation seems to be most luxuriant, comparatively 
speaking, about the central part of the chain of keys, say from 
` Key Largo to Key West. At Key West it has an appearance of 
decline, though it is hardly a fair point of comparison, as ™ 
of the trees suitable for fire-wood have been destroyed and many Os 
trees and plants introduced which have changed the aspect do 
the vegetation. West of this, however, the change becomes more ae 
marked, until finally we reach the Tortugas, where I made wa o 
point to try to collect every plant growing on the group. I think 
I nearly succeeded, and obtained only fourteen species, which my 
