33 
These mangrove swamps are particularly abundant along salt 
or brackish shores, and, as might be expected, occur frequently 
along the sea-islands, the so-called Florida Keys. Many of the 
keys observed during our trip to this interesting region were 
surrounded by a belt of mangrove trees, some of the smaller 
ones being entirely given over to this particular tree, while others 
had the interior covered, as in the hammocks of the mainland, 
with hard-wood trees and shrubs and vines. The formation 
here, as on the mainland, is of coral origin, but the rock is even 
more prominent and accompanied by less soil. Nevertheless, 
the pine-apple industry is a flourishing one, many acres being 
under cultivation and devoted to the growth of this fruit. The 
slips are inserted in the cavities of the rock, with no attempt at 
arrangement, and make a wonderful growth. The scarcity of 
the soil, however, renders a prolonged use of a field impossible, 
on account of the early exhaustion of the soil, and a new clear- 
of land is made imperative. We were informed that the 
abandoned fields are soon recovered with a new growth of tropical 
vegetation, and at the expiration of a number of years become 
again available for cultivation. 
andings and collections were made on three of the keys, viz.: 
Elliott's Key, Old Rhodes’ Key, and Totten’s Key. On allo 
them we found the uncleared portions heavily wooded, but, as in 
the hammocks on the mainland, very little herbaceous vegeta- 
tion occurred. A peculiar feature of the vegetation, and one 
hardly to be expected as an associate with the tropical hard-wood 
trees, is a species of Cereus. This was very common, its strag- 
gling 3-angled thorny stems sometimes attaining a length of 
twenty-five feet and sprawling on the ground or leaning on the 
surrounding vegetation. Another plant, quite in keeping with 
the Cereus, was a species of Agaiv, also of frequent occurrence. 
Insect life, represented by mosquitoes and highly ornate spiders, 
was very abundant, but of other animal life there was little; the 
almost entire absence of bird life made the silence of the woods 
intense. 
In order properly to make this trip to the keys, it was neces- 
sary to secure a naptha launch. The one we hired was about 
