GENUS ^Metridium^ ^M. marginatum.^ This is the most conspicuous and abundant sea-anemone of the northeastern coast. It is common from New York [pg145] northward, and is found near low-water mark in tide-pools, on the under side of large stones, in sheltered crevices of rocks, and on the piles of wharves and bridges. In contraction it is a broad, low cone, but when expanded is sometimes ten inches across the disk. Allied species found in Florida are eighteen inches in diameter. The column is smooth, cylindrical, and broader than long. At the top is a slightly elevated, thickened fold, and above this a deeply folded and frilled margin, with numerous fine, short tentacles, appearing like a fringe, which cover the upper side of the disk half-way to the oval mouth. The color is exceedingly variable; commonly the column is yellowish-brown, but it may be pink, white, salmon, orange, or dark brown, or striped or mottled with different colors. The disk and folds are lighter or flesh-colored, and the tentacles are of varying colors, usually grayish with tips of brighter colors. When irritated this species throws out from the column numbers of long, slender white threads (/acontia/), which are covered with minute stinging-cells. These organs of defense protect the animal from the attacks of many enemies. GENUS ^Rhodactinia^ ^R. davidsii^ (Agassiz), ^Tealia crassiformis^ (Gosse), the thick-petaled rose-anemone. The color varies, being often bluish-green mottled with crimson, often bright cherry-red, with the thick tentacles somewhat lighter in shade, or flesh-colored. The animal is found in shallow water. It assumes various shapes, changing every few minutes. The tentacles are short, conical, and uniform in size; the column, the breadth of which is greater than its height, often has wart-like processes in longitudinal lines. The diameter of the disk is about three inches. Found from Cape Cod northward in tide-pools and on ledges covered with /Fucus/. GENUS ^Holocampa^ ^H. producta.^ Its column, stretched to its full extent, is a foot in length and about an inch in diameter, but when contracted is much shorter and thicker. It has but twenty tentacles, and these have swollen tips. Rows of suckers extend the length of the column. It ranges from Cape Cod to South Carolina, and is found under rocks at low-tide mark, and also on sandy beaches, buried in the sand, with its tentacles only above the surface. GENUS ^Sagartia^ ^S. leucolena^, the white-armed anemone. It ranges from Cape Cod to North Carolina, and is common in Long Island Sound, being found at low-water mark on the under side of stones. The column is elongated, cylindrical, translucent, flesh-colored, with simple plain disk and long, slender, whitish tentacles crowded together near the margin. [pg146] ORDER =MADREPORARIA= STONE- OR REEF-CORALS