284 STAR-FISH FEEDING ON THE OYSTER. 



begins his attack by inserting an arm, but he does 

 not believe that the oyster tinder such circumstances 

 escapes with life. Let us suppose the star-fish to 

 have succeeded in insidiously introducing a ray 

 within the shell of the apathetic oyster, and that the 

 oyster immediately resented such intrusion by closing 

 his shell with all the force he can exert. The oppo- 

 site argument at this stage is, that the intruder is 

 obliged from pain to abandon his hold, and even pay 

 for his audacity by the forfeit of a limb. But 

 against this we advance the notorious fact, that the 

 star-fish, like so many marine creatures of a similar 

 organization, is remarkably indifferent to pain. I 

 therefore believe the true explanation to be, that the 

 oyster being unable to sustain such continued mus- 

 cular exertion for nearly so long a time as the star- 

 fish can tolerate the pressure upon its ray, the latter 

 is consequently, in the long run, successful. 



The number of rays in the several genera of the 

 true Star-fishes is extremely various. In the genus 

 U raster y as we have seen, five is the predominant 

 number. If we turn to the two species which com- 

 prise the genus Cribella, we still find the quintuple 

 arrangement adhered to. In Solaster endeca, on the 

 contrary, the rays vary from nine to eleven, and 

 even reach as high as twelve or fifteen in Solaster 

 papposa. 



In the genus Palmipes we have the pentagonal 

 form, it is true, but the space between each ray is 



