XIV] 



OPHIUROIDEA 



Class II. OPHIUROIDEA. 



339 



The next order of Echinoderras is termed the Ophiuroidea (Gr. 

 6<f>iovpo<s, serpent-tailed ; elSos, form) or the Brittle- stars. These like 

 the star-fish have a body with five arms diverging from a central 

 disc on all sides like the conventional representation of a star. The 



FIG. 155. 



Dorsal, upper or aboral view of Ophioglypha bullata x about 2J. 

 From Wyville Thompson. 



arms are, however, sharply marked off from the central disc, and 

 they do not, as in the true star-fish, insensibly merge into it, but 

 are continued along grooves on the under surface to the immediate 

 neighbourhood of the mouth: further they are exceedingly long 

 and flexible and totally unlike the stiff arms of Asterias or its 

 allies. 



222 



