The /Actiniaria/ are developed from the egg. The eggs form on the edges of the inner walls (mesenteries), and when mature drop into the outer sac (gullet), and out of the mouth as ciliated spheres (planulæ). After swimming about for a time these attach themselves to rocks, and, conforming to the irregularities of the surface, secure a tight hold. The upper surface of the planula then becomes depressed and forms a gullet, and in time a complete animal is formed. The /Actiniaria/ reproduce also by budding. A small protuberance or simple elevation of the body-wall appears on the side at the base, or in some species on the disk of the animal, which generally develops into a complete animal and at maturity falls away from the parent. Sometimes several anemones bud simultaneously from the same individual, and a third generation commences to bud at the same time from the immature young of the parent stock. The sea-anemones increase [pg144] also by self-division. In this case a constriction is formed, which gradually deepens and forms a complete partition of the body, and two individuals exist where originally there was but one. The /Actiniaria/ are carnivorous and very voracious. They feed on small organisms and on shell-fish and crustaceans, which they suck out of their shells. To secure their prey they are armed with an abundant supply of stinging-cells on the tentacles, and also with fine stinging-threads which are ejected from pores which are distributed over the whole body. Sea-anemones vary greatly in color and form, and when expanded suggest flowers, but do not resemble the one for which they are named. They abound on every shore, the same genus often being found in widely separated regions. They are larger and more highly colored in tropical waters. Many of the species are littoral, and are found in the tide-pools of rocky caverns, on the under side of rocks, and on the piles of wharves and bridges at low-water mark. The majority of them are attached, but are able to change their location; others, /Edwardsia/ and /Cerianthus/, swim about when young, and in the adult state burrow in the sand or mud, leaving only their tentacles exposed. /Bucidium parasiticum/ is parasitic on the folds of the membrane which hangs from the mouth of the large jellyfish /Cyanea arctica/. /Fenja/ and /Peachia/ lie on the sea-bottom, with their bodies horizontal like a worm, the mouth-end and tentacles erect. /Adamsia palliata/ furnishes another example of commensalism; it lives on the back of shells, commonly the whelk, inhabited by hermit-crabs. /Minyas/ is pelagic; it has a float at one end, and by means of its tentacles swims about freely. A very few species only are described below, since these polyps are unmistakable, being always columnar bodies, with the upper disk more or less crowded with tentacles, and so brilliant in coloring and beautiful in form as to attract attention if found in the expanded state; otherwise they are easily overlooked.