110 MARINE ANIMALS OF MASSACHUSETTS BAY. 



(Fig. 143), around which the pedicellariae are arranged in a close 

 wreath, in the centre of which the summit of the spine projects ; 

 they differ also from those of the Sea-urchin in having two 

 prongs instead of throe. Other pedicellariae are scattered inde 

 pendently over the surface of the animal, but they are smaller 



Fig. 142. 



than those forming the clusters and connected with the spines. 

 The function of these organs in the Star-fish remains unexplained ; 

 the opening on the upper surface, through which the refuse food 

 is thrown out, is in such a position that they evidently do not 

 serve here the same purpose which renders them so useful to the 

 Sea-urchin. Occasionally they may be seen to catch small prey 



Fig. 142 Star-fish ; natural size, seen from above. 



