STAR-FISHES. 



223 



portion gradually merging into the rays. Beneath 

 each ray there is a large number of locomotive suck- 

 ers, like those of the sea-urchins already described. 

 These tubes are seen in Figure 468, where the upper 



Fig. 468. Star-Fish. 



part of the Star-Fish is towards you, and three of 

 the rays slightly turned backward. The mouth is 

 on the under side in the centre, and there is an eye, 

 or eye-spot, at the end of each ray. By means of 

 the ambulacral tubes Star-Fishes move slowly but 

 surely over the rocks and all kinds of surfaces, and 

 they can cling to the rocks so firmly that they are often 

 removed with difficulty, and will sometimes even allow 

 their ambulacra to be pulled off rather than let go 



