10 FLOEIDA REEFS. 
An endless variety of Gorgonias, for the most part too little known yet 
to be fully characterized, grow in tufts between the coral heads or upon the 
coral sands and in the mud flats. Among them are the Halcyonia growing 
in clusters, the branching Gorgonias forming dense bushes, and the beautiful 
sea-ftms, a kind of Gorgonia, the branches of which spread in flat expansions 
forming a network of anastomoses, the meshes of which are covered with 
distinct animals. Again, innumerable polyps, like mollusks belonging to the 
lower fiimilies of that class, spread over the same ground, frequently aping, 
in their manifold combinations, the diversity of corals on which they rest. 
So similar are some of them to the true corals that they have only recently 
been recognized as mollusks, and referred to that type under the name of 
Bryozoa. Among them is one species of particular interest for the geologist, 
because it is the first livino- analogue ever found of that curious extinct 
family, the Graptolites, so common among the oldest fossiliferous rocks. 
Its modern representative was discovered in the shoal w^aters of Key West. 
The Echini are more numerous here than upon any other part of the 
American coast. They belong to the genera Echinus, Tripneustes, Dia- 
dema, Cidaris, Clypeaster, and Encope. We found no Spatangoids, though 
they are known to occur on the West India Islands. The Diademas are 
found among the coral boulders, generally in nests together, frequently 
concealed in the larger excavations of the coral heads. The Clypeastei's 
and Encopes on the contrary, live upon the coral sand flats, wdiile the 
Cidaris prefer the shoal grounds of the Corallines and Nullipores. Holothuria 
swarm in myriads upon the mud flats; suggesting by their numbers the 
feasibility of collecting them for sale as Trepang. This is an important 
article of commerce in China and the East Indies, and their edible species 
resembles ours so closely that I believe the latter might be used in the 
same way and furnish a profitable industry. So may the sponges of 
Florida, for which there is already considerable demand. Beside this 
wealth of animal life, the reef abounds in tropical sea-weeds. Of these the 
well-known Gulf-weed is the most striking. It seems strange that the 
origin of these floating weeds should be doubted when they are found grow- 
ing so abundantly. Even a brief description of the inmiense number of 
shells, worms, crabs, lobsters, shrimps, craw-fishes, and fishes, seen every- 
where upon the reef, would be out of place here. In variety, in brilliancy 
of color, in elegance of movement, the fishes may well compare Avith the 
most beautiful assemblage of birds in tropical climates. 
