STAR.FISHES, SEA-URCHINS, ETC. 79 



farthest limit. But it difters in many details of 

 structure. The mouth in the Synapta is surrounded 

 by a wreath of branched tentacles, into whose in- 

 terior the sea-water is admitted through a system 

 of vessels connecting with a madreporic tubercle. 

 The latter structure, as in all other sea-cucumbers, 

 is placed near the mouth. 



Closely examined, the transpai'ent wall of the 

 body will be found to be speckled with minute 

 wart-like processes, giving the animal a rough feel 

 when taken in the hand. These processes under a 

 microscope reveal most extraordinary forms, which 

 are most nearly likened in outline to an anchor : 

 hence we speak of the anchor-like spicules em- 

 bedded in the body-substance, which of themselves 

 frequently offer good characters in the determina- 

 tion of species. In some forms, as in the remark- 

 able pangolin-like Psolus of the New England 

 coast, these processes, or rather their representa- 

 tives, are developed into an armor of stout over- 

 lapping scales or plates. 



Placed in a dish of sea-water, the habits of this 

 interesting creature can be studied at leisure, the 

 regular rhythmic or wave-like motion of the body 

 proving a never-failing source of surprise to those 

 to whom the animal is a novelty. At some mo- 

 ments it has contracted into a nearly perfect ball, 

 at other times it has straightened itself to double 

 its usual length. Frequently it throws off parts of 

 the posterior end of its body, accomplishing this 

 curious freak either by close constriction, or by the 

 forcible expulsion of its intestines. In feeding, the 



