134 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 180. 



Fisr. 181. 



Fig. 180. Young Sea-urchin older than Fig. 179 ; 1 1' tentacles, s" s'" spines. 



Fig. 1S1. Still older Sea-urchin ; 1 1 tentacles, a anus, p pedicellariae ; shell one sixteenth of an inch 

 in diameter. 



