OCEAN LIFE. 37 



trusion and retraction are effected in the same manner. The 

 mouth is a round aperture, as wide as a goose-quill, placed in 

 the centre of a raised ring at the anterior extremity of the body. 

 Around the oral orifice is placed a circle of tentacula, which are 

 apparently extremely sensible, and serve perhaps not only as in- 

 struments of touch, but as prehensile organs used for the cap- 

 ture of prey, or for assisting in deglutition." 



" Sir John Graham Dalyell stated in 1840 that he had observed 

 the Holothuriae lose the tentacula, with the cylinder (dental ap- 

 paratus), mouth, ossophagus, lower intestinal parts, and the 

 ovarium, separating from within and leaving the body an empty 

 sac behind. Yet it does not perish. In three or four months 

 all the lost parts are regenerated, and a new funnel, composed of 

 new branches as long as the long body of the animal, begins to 

 exhibit the same peculiarities as the old one, though longer time 

 be required to attain perfection. Other species of the Holothu- 

 ria divide spontaneously through the middle into two or more 

 parts, all becoming ultimately perfect by the development of 

 new organs. Yet the anatomical structure of the whole genus 

 is so complex as to defy the skill of anatomists in discovering 

 the proper functions of some of the parts. A single Holothuria 

 has produced 5000 ova in the course of a night. Of one genus, 

 the Trepang, many species are eaten. In Mr. F. D. Bennett's 

 interesting 'Account of a Whaling Voyage round the Globe,' 

 we are told that there are two kinds of Trepang abundant on the 

 rocks at Raiatia, and they are very indolent animals. ' When 

 handled,' says Mr. Bennett, Hhe Trepang contracts its body in a 

 longitudinal direction, and should its tentacles be expanded they 

 are instantly concealed ; but no noise or agitation of the sur- 

 rounding water will excite these symptoms of alarm, or cause 

 any attempt to escape. They usually lie exposed in the shallow 

 waters, though we have very often seen them buried in beds of 

 coral sand, their plumy tentacles being alone exposed, and float- 

 ing in the water above, apparently as a lure for prey. Some 

 may also be observed lying on the rocks, their bodies completely 

 encrusted with coral sand, which may either have been accumu- 

 lated by a previous burrowing, or thus used as a disguise. It 

 would appear to be partly the instinct of the animal to take its 



