114 ' THE HALL OP SHELLS. 



formed almost entirely from their broken stems 

 and flowers. 



" Once the glory of the sea, they have 

 dwindled to a few species, inhabiting for the 

 most part the deepest seas." 



The following may be helpful in giving an 

 understanding of the classes of EcTiinodermata. 

 First we have the Orinoidea, which are really 

 stalked starfishes, the body mounted upon a 

 stem ^vhich is jointed and hollow ; second, the 

 Asteroidea, which are free and have five arms ; 

 third, JEcIiinoidea, having a spherical body, 

 with long spines; fourth, the IIolothuroid<B, 

 having elongated bodies, with skin soft or 

 muscular. 



