T1ABITS AND DISTRIBUTION. The modern Coma tulidic, like Antedon, Aetinometra, etc., have a very wide distribution, and are usually found in waters less than 150 fathoms in depth, although one species of the Antedon has been dredged from the great depth of 2900 fathoms. The habits of Antedon are best known. It is a gregarious ani mal and Verrill has obtained 10,000 individuals in a single trawl in the North Atlantic. It lives mostly in the upper layers of the water, but when exposed to the direct rays of the sun, it curls up its arms and sinks. When clinging by its cirri to a em-al or rocky point and disturbed, it releases itself immediately and swims away by graceful movements of the arms, or crawls on its arms like a spider over the bottom. Sudden changes of temperature stun it ; it sinks to the bottom and soon dies. When these animals find themselves in uncomfortable surroundings, as when taken in the dredge and placed in aquaria, they drop off their arms, which break at specially fused joints, called 'syzygies,' but the arms are restored through regeneration if the erinoid survives. The
stalked crinoids are also gregarious animals, hut they are more restricted in their distribution, and inhabit deeper waters. The majority of fossil stalked erinoids are found in rocks that were un doubtedly comparatively shallow-water deposits, and because the calcareous plates of the calyx, and to a lesser degree those of the stem, fall readily apart after the death of the animal, per fect specimens are quite rare finds. The food of erinoids has been ascertained to consist of minute crustaceans, diatoms, spores of alga?, fora minifera, and radiolarians.