S44 ITS STEUCTUEE AND HABITS. 



longitudinal colourless lines, of which the dorsal ones 

 are only half as hroad as the ventral. Under a lens the 

 ground colour is resolved into a numher of minute red 

 dots, thickly placed dorsally, and often hecoming con- 

 fluent into longitudinal dashes, hut placed thinly on 

 the helly. 



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 hranches into 

 four short diverging fingers, which are likewise taper 

 and pointed. The red speckling extends up the ten- 

 tacles. The mouth is a cup-shaped circular cavity, 

 whose edges reach to the bases of the tentacles. 



The dental cylinder of the Holothurim 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 whfch I received 

 them ; very soon one after another began to constrict 

 the body into knobs at irregular intervals, occa- 

 sionally so forcibly as to separate into two or manv 

 pieces. Sometimes the division was incomplete, 

 so that the intestines, and especially the long gene- 

 rative threads were forced out abundantly from the 



