STRUCTURE OF THE CRINOIDEA. 



647 



proceed articulated arms or tentacula, When the animal 

 is alive, the skeleton is covered by a soft integument, as in 

 the Star-fishes ; the mouth is situated on one side of the 

 centre of the receptacle, which is surrounded by the arms 



Lign. 144.— The body, and upper part of the stem of a 

 Pentacrinus. 



(From the West Indian Seas.) 



that spread out and expand into a net to capture the living 

 prey, and, like the tentacula of the hydra, seize and convey 

 it to the mouth. I scarcely need remark that the Crinoidea 

 are individual organisms, and are never aggregated and 

 united by one common axis, as are the compound Polyparia 

 that lately engaged our attention. There are some fossil 



