FLORIDA REEFS. 17 



and one sinks ankle-deep in the dense coral growth. A most astonishing 

 variety of sea-worms is found between the branches of the Porites and 

 Oculina. This is also the play-ground of many Ophiurans and Asterians. 

 Cidaris metularia are found here also, and other species of Echini. Such 

 mud-shoals, composed of the most minute sand and mud, frequently encircle 

 the keys, often extending for miles beyond their shores. Wherever they 

 are laid bare at low water they are overgrown by Milleporas ; but where 

 they are always covered, even at the lowest tides, with a few inches of water, 

 the Porites take the ascendency. The latter are chiefly of two species, the 

 Porites furcata and Porites clavaria. A black Ascidian is often attached to 

 their branches in great numbers. Great numbers of Holothurians make their 

 home upon these mud flats. Large holes, sometimes close together, some- 

 times at small distances from each other, are frequently to be met with. 

 These holes, widening at the surface in the shape of a funnel, having a depth 

 of several feet and a diameter of several inches, are occupied by a gigantic 

 worm of the genus Eunicea. Large Actiniae of various colors are also numer- 

 ous, and a deep orange colored Starfish and Manicinas show themselves 

 also, though not in great numbers, and an endless variety of Gorgonias. 

 Such shoals are the best field for the collector. Similar mud flats are found 

 everywhere around the Mangrove Islands. But of these, more presently. 



Soldier Key rises about five miles to the south of Cape Florida. It is 

 connected with an extensive mud flat, which stretches nearly to the lighthouse, 

 being separated from it only by a narrow channel from nine to ten feet 

 deep. The Ragged Keys conae next, — a series of some half-dozen small 

 islands formed by coral boulders rising but little above the surface of the 

 water, and surrounded on both sides, and especially on their western shores, 

 by wide mud flats. These keys, as well as Soldier Key, are covered by man- 

 groves. It is noticeable that some of the Mangrove Islands have beaches, — 

 a fact explained by their mode of formation. To the westward follows 

 Elliott's Key, the first whose surface does not consist solely of coral boulders, 

 coral sand having formed a succession of layers of oolitic rock upon it. Here 

 also we first find white sand beaches dipping to seaward, and see a variety 

 of trees mingling with the mangroves. On the southernmost extremity 

 there is a spur formed by a mud flat, while another more extensive one 

 juts to the eastward, and is connected with Old Rhodes, the next key. Key 

 Largo, which follows, is the largest of all the islands in the main range of 

 keys. It is not less than twenty-five miles long and from one to three miles 



