280 FLORIDA GEOLOGICAL SURVEY-THIRD ANNUAL REPORT.
The Cladium, Eupatorium and Sagittaria are especially characteristic of the marshes bordering the lake, while most of the other herbs grow along the bayous in the swamp. Most of the plants in this list have already been mentioned as characteristic of calcareous swamps.
The peat in the marsh, as far out as I was able to go, was about 20 feet deep, which is considerably above the average. In the swamp at the point tested, which was where the railroad crosses one of the bayous, the peat was so full of logs that it was difficult to push a sounding instrument into it very far, but it seems to be at least 12 feet deep.
In both swamp and marsh the peat is brown, moderately coarse, with a slight sulphurous odor. A most interesting feature of this peat is that it contains numerous univalve shells (a fact which was discovered by Dr. Sellards about four years ago). The shells are especially abundant in the bayous, at depths exceeding four feet.
A small sample of this material from 6 feet below the surface of the water (which was only a few inches deep) in one of the bayous, collected April 23, 1909, was examined by Dr. W. H. Dall of the U. S. National Museum, with the assistance of Dr. H. A. Pilsbry of the Philadelphia Academy of Natural Sciences, and a list of 15 shells, including one new species, found in it was published by Dr. Dall in The Nautilus for May, 1910io. On May 16, 1910io. I collected a larger quantity of peat from the same spot, at a depth of 4 to 5 feet, and in this the following species have been indentifled by Bryant Walker, Esq., of Detroit, Mich.

Amnicola angustina Pilsbry Amnicola Floridana Frfld.? Amnicola Harperi Dall Amnicola Sancti-Johannis Pilsbrv Amnicola sp.
Amnicola sp. Ampullaria sp. (very young) Ancylus obscurus Hald. Gillia Wetherbyi ].D)all? Goniobasis catenaria Say (G. pap
illosa Anth.)
Lymnaea cOlumnella Say Paludestrina acquicostata Pilsbry Paludestrina monas Pilsbry

Physa Cubensis Pfr. Pisidium sp. Planorbis Alabamnensis avus Pilsbry
Planorbis dilatatus Gld. Planorbis parvus Say Planorbis trivolvis Say Planorbis tumidus Pfr. Polygyra sp. Succinea sp. Vertigo ovata Say Vivipara Georgiana Lea? Vivipara Haleana Lea

All or nearly all of these are said to be found still living in Florida, so that their presence in this peat deposit does not indicate