THE STARFISH AND SOME ALLIES 245 



The central disk is more distinct in the basket-fish than in 

 the starfish. The five arms, instead of being single, divide 

 and redivide many times. The sieve-plate lies on the oral 

 surface. There is only one opening to the .digestive system, 

 the mouth. The tube-feet do not extend to the outside, 

 hence they are not used for locomotion, that activity being 

 accomplished by the branched arms, controlled inside by mus- 

 cles. Respiration takes place through little pockets which 

 open into the central disk from below. 



Only in the rarest instances is it possible to learn anything 

 of the activities of the basket-fish. Mr. A. Agassiz and Mrs. 

 E. C. Agassiz give an interesting account of it in Seaside 



ni. 122. Photograph of Basket-Fish, x \ 



