Page:The aquarium - an unveiling of the wonders of the deep sea.djvu/299

244 longitudinal colourless lines, of which the dorsal ones are only half as broad as the ventral. Under a lens the ground colour is resolved into a number of minute red dots, thickly placed dorsally, and often becoming confluent into longitudinal dashes, but placed thinly on the belly.

The anterior extremity forms a disk surrounded by a marginal circle of twelve short tentacula. These organs are rather thick columns, with their bases in contact, tapering to the tip, where each branches into four short diverging fingers, which are likewise taper and pointed. The red speckling extends up the tentacles. The mouth is a cup-shaped circular cavity, whose edges reach to the bases of the tentacles.

The dental cylinder of the Holothuriæ is represented by a slender ring of minute white calcareous pieces, varying in size, and irregular in form. None of them are larger than th of an inch square. They are united by cartilage into an elastic ring, running round the base of the tentacular circle.

While in captivity the motions of these animals were quite vermicular, slowly twisting the long body into knots and contortions, and writhing about. The tentacles were now and then bent inward to the mouth, one or two at a time, and then unfolded. They did not long retain the cylindrical form in which I received them; very soon one after another began to constrict the body into knobs at irregular intervals, occasionally so forcibly as to separate into two or many pieces. Sometimes the division was incomplete, so that the intestines, and especially the long generative threads were forced out abundantly from the