718 THE SEA CUCUMBERS. 



in which they can alter their shape. In consequence of this extremely contractile 

 structure, the whole of the water contained in the body is spirted out as soon as a 

 wound is made, and intestines are seen to be forced out after the water. One species 

 of Thalassema is used as bait by fisherman. 



All the species on the preceding engraving belong to the family Sipunculidae, ind 

 are found in British seas. 



The specimens on the above and the next two illustrations belong to the family 

 HOLOTHURID^E, and are popularly known by the name of SEA CUCUMBERS or SEA PUD- 

 DINGS. In these the body is mostly cylindrical, and is covered with a tough leathery 

 skin, upon which are placed a number of scattered chalky particles. The mouth is 

 surrounded with a set of retractile tentacles. 



Psollaus brevis. 



Psolus phaatapus. (Two figures,) 



Some species of this family are eaten by the Chinese, and a large trade is carried on 

 in these strange products of the sea ; the annual merchandise being worth about two 

 hundred thousand pounds. The price of the TREPANGS, as they are called, is very 

 variable, according to the species, some kinds being comparatively cheap, and costing 

 rather less than two pounds per hundredweight, while others will fetch thirty pounds 

 for the same weight. There are, besides, "fancy prices" for some very scarce species 

 of Trepang, which, however, are likely to be equalled in real value by the cheaper and 

 commoner kinds. In the British Museum may be seen a valuable collection of the 

 various kinds of Trepang, with their prices attached. 



They seem to be very unattractive creatures, black, wrinkled, and looking much as if 

 they had been made out of the upper-leather of old shoes. They are, however, convei tible 



