24 FLORIDA REEFS. 
MadreiDora palmata) as with a close shrubbery. One is reminded of the 
bank or beds of Kalmia or rhododendron spreading so uniformly over cer- 
tain favorable spots. These beds of Madrepora palmata are yellowish in 
color, and broken here and there by a few heads of Millepora alcicornis or 
Ma^andrina labyrinthica. The growth is so close that there are hardly any 
intervals to be filled by dead corals. Only on the borders of the ledge, and 
especially to the leaward where it slopes to the ship-channel, do we find 
accumulations of coral sand and coral debris between the heads of the Mtean- 
drinas and Porites. These become more numerous as the depth increases, 
and are accompanied by a great variety of Gorgonia. Within the ship- 
channel the accumulation of coral sand increases, and several sand ridges 
may be traced parallel to Carysfort Reef along its inner slope, rising to some 
eight or nine feet below the surface of the water. Upon these sand ridges 
may be seen occasional heads of Mteandrina, patches of Millepora and Mad- 
repora, and also a variety of Gorgonia, especially the beautiful purple Gor- 
gonia flabellum, known as the sea-fan. On the steep seaward slope, 
and below the range of the Madrepora palmata, the heads of Ma^andrina 
and Porites are very numerous. To the west of Carysfort, the edge of the 
reef sinks to a depth of some nine or ten feet, the greatest depression on the 
reef west of Cape Florida. Between the reefs above mentioned, for instance, 
there is hardly anywhere more than six or seven feet of water, so that 
from Fowey Rocks to Carysfort Reef we have an mibroken range of living 
corals. French Reef, again, is separated from Pickle's Reef by a depression of 
about ten feet, as is also Conch Reef from Crocker's Reef Between this and 
Alligator Reef the depression is still greater; about twelve feet. The outer 
reef itself rises for a longer stretch near the surface at Alligator Reef than 
anywhere else west of Carysfort or east of Sombrero. Between Alligator 
and Tennessee Reefs, and between these and Coffins Patches, there is upon 
the edge of the reef not less than fifteen to seventeen feet of water, and 
about twenty between Coffins Patches and Sombrero. Sombrero is a small 
island of a few acres, formed of large coi-al fragments heaped up on the edge 
of the reef Between Sombrero and Looe Key another large depression 
occurs on the reef some twenty feet deep throughout. 
Thus not only are the higher ledges upon the reef gradually separated by 
wider intervals, but the reef itself, as a whole, is deepening westward, as is 
shown by the increasing depth and extent of the depressions. In fact the 
reef, as well as the mud flats, dips from east to west. At Looe Key, a small 
