OPHIUEA. 165 



jointed and flexible rays of Gorgonocephalus still form so many legs, 

 enabling the creature to drag itself along the bottom of the sea, or to 

 entwine itself among the submarine plants, as well as supplying the 

 office of tentacula in securing food. 



(437.) Continuing our progress towards more perfect forms of these 

 remarkable animals, we at length arrive at genera in which the rays 

 become divested of all elongated appendages, either in the shape of arti- 

 culated lateral filaments or dichotomous ramifications. In Qpliiura, 

 for instance (fig. 83), the rays are long and simple, resembling the tails 



Fig. 83. 



Ophiura. 



of so many serpents a circumstance from whence the name of the 

 family is derived ; nevertheless, on each side of every ray we still trace 

 moveable lateral spines, which, although but mere rudiments of what 

 we have seen in Comatula, may yet assist in locomotion, or perhaps may 

 contribute to retain the prey more firmly when seized by the arms. 

 The rays themselves are composed of many pieces curiously imbricated 

 and joined together by ligaments, so that they are, from their length 

 and tenuity, extremely flexible in all directions, and serve not only for 

 legs, adapted to crawl upon the ground, but are occasionally serviceable 

 as fins able to support the animal in the water for a short distance by 

 a kind of undulatory movement. The body, or central disk, is beauti- 



