CLASS CEIAOIDEA. 263 



CLASS IV. CRINOIDEA. 



General Characteristics. The Oinoids (lily-form) are 

 Echinoderms that during a portion or the whole of their 

 lives are fixed to some solid body by a foot-stalk (peduncle). 

 They strikingly resemble a flower. The mouth is in the 



Fig. Uh9. 



Comatula rosac$a, Rosy Feather-star. Adult free Crinoid. 



centre, with arms springing from the disk or calyx, but 

 speedily ramifying until the complete internal skeleton, 

 exclusive of the stem, consists of many thousand joints. All 

 parts are covered with a fleshy integument, dipping down 

 between each joint. Some of the species remain fixed for 

 life, while one at least (Comatula) is known at maturity to 

 drop from the stem and ever after to wander free. (See 

 "Geology," pp. 129, 153, 171.) 



