to their meat-hunting fellow-denizens of the sea. They have an exceedingly rare peculiarity. When one excites them, handles them roughly, or takes them out of the water, they contract their musculous body convulsively, and vomit themselves out—not only the contents of their stomach or intestines, but the intestines with the contents. But this self-mutilation, apparently so terrible, is not as bad as it seems to be. The intestine is capable of replacing itself, and, after a short season of fasting, our sea cucumber is again restored to its former condition. This is a remarkable phenomenon of a regeneration or restitution process, not yet sufficiently investigated. The holothurias are, like all the spiny-skinned animals, exclusively inhabitants of the sea; at least no fresh-water form is known. In the sea itself, however, they are of universal occurrence. Their representatives are found from pole to pole, and in all depths, from those of only a few metres to those of a thousand metres and more.
A former officer of the Dutch East Indies, M. Lion, who is thoroughly acquainted with the characteristics of that remarkable region, says that there is not an island in the Indian Archipelago near which the trepang is not found; and this is confirmed by the Englishman Jamieson, who marks as the home of the animal
Fig. 3.—Infancy of a Sea Cucumber. A, a jelly animal swimming and feeding; a, small sea cucumber forming inside. B, the young sea cucumber with the leaf-like tentacles round its mouth, walking on its tube feet. all the seas from Sumatra to New Guinea. The trepang can be found everywhere in this region when the surf is not too strong, chiefly at depths of from six to nine metres, on flats covered with coral sand, but not on muddy bottoms. Here they feed, as the English author Guppy has described them to us. An individual of any of the species of trepang from twelve to fifteen inches long will eat half a pound of weathered coral sand a day, loosening it from the surface of the reef. The term eat, however, is hardly the proper one. The animal lets the mass, which contains only a trifling fraction of nutritive matter, pass through its intestines. Fifteen or sixteen of these animals would thus dispose of a ton, or about eighteen cubic feet, of sand in a year. Mr. Guppy speaks of an "organic denudation," of a process of weathering of the coral reef, in course of accomplishment through living causes.
"The Celestial Empire," says Mr. Jamieson, "could not exist without trepang and East Indian birds' nests; and the inquiry for
