THE HTARFISII 



257 



to small plates lying in the skin. The mouth is suiTOundecl by 

 a circle of tentacles (Fig. 249) . The ambulacral feet are some- 

 times a1)sent. The Holothurians live in sand and mud, often 

 deeply buried, and feed on small marine animals or the decay- 



FiG. 248. — View from mouth side of a sand-dollar (Mellita). From Lang. 



ing particles mingled with the mud which they devour. They 

 are of considerable economic importance. The members of 

 one genus (Holothuria) are taken in great numljers on the 

 coral reefs of the Pacific Ocean and the China Sea, where they 

 are commonly known as " trepangs." Thev are cut open, 

 washed, boiled, dried, and sometimes smoked. They are sold 

 in Chinese ports and some species are con.sidered by Chinese 

 epicureans as great delicacies, being cut up into small lumps 

 which are boiled to make a soup. 



