Shells found in Essex County. 65 



Bf3autiful varieties may be obtained by careful search. Those 

 thrown upon our beaches present little interest, being bleached 

 in the sun. A favorable locality is on the flats and rocks, near 

 Beverly bridge. 



The fibres and sometimes the entire leaves, (fronds) of spe- 

 cies of sea weed (Algae) are often seen upon these shells. The 

 Laminaria or kelp is not an unfrequent companion. This being 

 produced from its seed-like bodies upon the shells, and growing 

 in a calm sea throughout the summer months, is of no probable 

 disadvantage ; but no sooner do the autumnal storms commence, 

 than the little shell fish is ungenerously torn from its situation, 

 by the agitation of its unwieldy parasitic neighbor, to be cast 

 upon the shore. Rolled pebbles of a large size are also lifted 

 from the bottom, by the simple and perfectly natural agency of 

 this marine vegetable. 



Common on the beaches of Essex Co. 



Cabinet of the Society. 



^ 



CREPIDULA PL AN A. Say. Latin, flat. . 

 Flat slipper Shell 



A very pretty, pearly vitreous species ; about an inch in 

 length ; found sometimes perfect, but more commonly much 

 worn. Diaphragm or deck occupying half the length of the 

 shell. Shell generally flat, but sometimes tortuous or reflexed, 

 according as it has resided on a plane or curved substance. 



Lynn beaches, rare. 



Described in Journ. Acad. Nat. Sc. Phil., vol. ii., p. 226. 



Say's Am. Conchol., pi. xliv. 



My Cabinet and that of the Society. 



ANCYLUS. Latin, a buckler. 

 RIVULARIS. Say. Latin, belonging to streams. 



River Jlncylus. 



Shell very small, exceedingly thin and yellowish, sometimes 

 white within when old and dead ; resembling a minute Patella. 

 Found under the leaves of the Yellow Water Lily, (Nuphar 

 advena L.) in ditches, ponds, and sluggish streams. 

 Journ. Acad. Nat. Sc. Phil., vol i., p. 125. 

 My Cabinet. 



