EMBRYOLOGY OF EOHINODERMS. 



133 



180 and 181 we have different stages of the little Sea-urchin, with 

 its spines and suckers of a large size and in fuU activity. The 



Pig. 177. 



Fig. 178. 



Fig. 179. 



appearance of the Sea-urchin, as soon as this larva or Pluteus is 

 ^completely absorbed, is much more Uke that of the adult than is 

 the Stai^fish at the same stages, in which, as we have seen, there 

 is a transition period of considerable duration. 



Fig. 177. Fig. 176 seen endways. 

 ■Me. 178. The Sea-urchin resorWng the arms of tlie larva. .;„.„ 



Fi|: 179. Half a yoang Sea-urchin in>mediately after resorption of the larva •, ." ." spmes, f t> «n. 

 bolacrsl tentacles. 



