THE SEA- CUCUMBER. 27 



among the rock- work of the tank ; pressing his body 

 between the pieces just as when we saw him first, but 

 taking care to leave space to protrude his front. Then 

 this part evolves, and a deep collar of dark purple is 

 seen, from which a ring of ten somewhat thick stems 

 arises, tapering to a point and arching outwards. These 

 are of a purplish-black hue, and are studded with short 

 branches set on in a spiral, which again branch and 

 branch again, each terminal point bearing a white 

 papilla ; so that the whole constitutes a series of conical 

 aggregations of white dots clustering about the black 

 stems, something like pointed cauliflowers, and forming, 

 as they wave to and fro in the clear water, a very 

 charming spectacle. 1 



The suckers, which, when the animal first came into 

 our possession, were apparent only as little warts, 

 arranged in five clustered rows down the angles of the 

 body, are now seen to be long tubes, each with an 

 adhering disk at its extremity, by which it anchors to 

 the surrounding stones. The mechanism of these 

 suckers does not importantly differ from that of the 

 same organs in the Star-fishes. Indeed, notwithstanding 

 the very wide diversity of form and appearance between 

 the two animals, the Cucumber and the Star are so 



i The principal figure in Plate in. represents this species (Pentacta 

 pentactes) in the expanded condition described in the text. 





