ZA. THE RADIATES. 



235. THE ECHINODERMS. 



THE SEA CUCUMBERS, OR TREPANG UOLOTHUKIA FLORIDANA, Pourtales ; HOLOTHURIA 



PRINCEPS ; PENTACTA FRONDOSA, Jteger. 



The Sea Cucumbers, or Holothurians, are the highest members of the group of Echinoderms, 

 whicli also includes the Sea Urchins aud Star-fishes. They usually have an elongate, cylindrical, 

 flexible body, covered with a muscular skin, which varies greatly in thickness in the difl'eivnt 

 species. The mouth is located at one end of the body, and is surrounded by a circle of more or 

 less complex tentacles or feelers. That division of the Hololhurians to which the economic species 

 belong are furnished with the so-called ambulacral feet, which are sometimes arranged in five 

 longitudinal rows or series, ami at others are scattered without order over the surface of the body. 

 The body wall frequently contains numerous minute calcareous plates, of various shapes, whicli 

 are often peculiar to the different species. Many of the species are quite worm-like in external 

 appearance. The Trepang of Chinese commerce is the dried skin of a large species of Ilolothurian 

 living in the South Pacific Ocean, and used as food iu China. 



The largest and one of the most conspicuous of the New England Holothurians is the PeutuHu 

 frondom, which inhabits the northern Atlantic coasts of both Europe aud America, from low-water 

 mark to a depth of one hundred fathoms or more. It is of a brown color, and measures from a 

 few inches to about a foot in length when expanded. The ambulacral feet form five double and 

 irregular rows, and the tentacles are ten in number, and much branched. Dr. William Stimpson 

 remarks concerning this species that, made into a soup, it is very palatable ; but it has never 

 been regularly used as food. 



Holothuria floridana is a large dark-brown species, with the feet scattered irregularly over 

 the body, and with smaller tentacles than Pentacta. It occurs abundantly on the Forida reefs, just 

 below low-water mark, and grows to about fifteen inches in length. Holothuria princeps is 

 another large Florida Sea Cucumber. One or both of these species, but more probably the former, 

 gave rise, about 1870, to a limited industry on the Florida coast, to be described hereafter. Large 

 quantities were collected on the reefs, cleaned of their internal organs, boiled, and then dried 

 and shipied to China; but the industry was abandoned after two years' trial, probably having 

 been unprofitable. Chinese coolies assisted in the work. 



THE SEA URCHINS STRONOYLOCENTROTUS DROBACHIENSIS, A. Ag.; STRONG YLOCENTROTUS 

 FRANCrsCANUS, A. Ag. ; EciIlNARACHNirs PARMA, Gray. 



The Sea Urchins are related to the Sea Cucumbers, but differ from them in form, and in the 

 character of their external covering. The body is generally somewhat spherical in shape, but 

 more or less flattened below, the mouth being placed near the center of the lower surface. The 

 outer covering is built up of calcareous plates, closely fitting together, from which project a 

 multitude of spines, sometimes of small, sometimes of large size, there being generally a great 

 variation in size in the same individuals. The larger spines are generally arranged in regular 



series. There is a water system; five double rows of feet, which run from the center above to 

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