134 MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 180. 



Fig. 181. 



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



Fig. 181. Still older Sea-urchin 5 1 1 tentacles, a anus, p pedicellaria? 5 shell one sixteenth of an inch 

 in diameter. 



