so 



Anriciila bidcntata. Abundant on tlio liynn marshes ; 

 and dead shells are sometimes found on the beaches at 

 Swampscot. 



Planorbis lentus. A rather common species. 

 Planorbis bicarinatus. Rare. 

 Planorbis armigerus. Very common. 

 Planorbis hirsutus. Common. 



Physa heterostropha. Occasionally found in a shaded 

 ditch by the roadside at Swampscot. 



Physa ancillaria. Found with the last mentioned spe- 

 cies ; also, found in other localities. 



Physa elongata. In a temporary pool of water, surroun- 

 ded by woods on the high land, and eastward of the village 

 of Swampscot. 



Limnaea columella. ) In some of the ponds and in 



Limnsea macrostoma. > marshy lands at Swamp- 



Limngea umbilicata. 3 scot. 



Limnaia elodes. Occurs common, with Physa heteros- 

 tropha. 



Ancylus fuscus. Attached to stones just below the sur- 

 face of the water, at Floating-Bridge pond, Lynn. 



Valvata pupoidea. Abundant with Ancylus fuscus. 



Paludina decisa. At Eel Brook, Swampscot ; but rare. 



Natica heros. Abundant on all of our beaches. 



Natica triseriata. Common on the flats of Lynn harbor. 



Natica immaculata. Common in all parts of the bay. 



Natica caniculata. In deep water ; rare. 



Natica duplicata, with Natica triseriata ; common. 



Natica pusilla.* ) In all parts of the Bay, not infre- 



Natica clausa.* \ quent. 



Yelutina lasvigata.* Common. 

 Velutina zonata.* Common. 



Sigaretus haliotoideus.* Off the Pig Rocks, near 

 Swampscot. 



Scalaria Grocnlandica.* Various parts of the Bay. Ta- 

 ken alive with the dredge in ten fathoms water, rocky bot- 

 tom, half a mile North East of Egg Rock, 



