134 MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 180. 



Fig. 181. 



Fig. 180. YouDg Sea-urchia older than Fig. 179 } t V tentacles, s" s'" spines. , 



Fig. 181. Still older Sea-urchin -, / 1 tentacles, a anus, p pedlceUaria; ; shell one sixteenth of an inch 

 In diameter. 



