Shells found in Essex County. 61 



The following belong to the second order of Lamarck, viz. 

 UNIMUSCULOSA, i. e. having but one muscular impression on each 

 valve. 



MODIOLA. Latin, a little measure. 

 PAPUANA. Lamarck. " Horse Muscle." 



A Genus invented by Lamarck, to denote some trifling distinc- 

 tion between this shell and Mytilus to which it is closely allied. 

 A better distinction is made by the celebrated anatomist Poli, on 

 account of some peculiar organization of the animal, and called 

 by him Callitriche. Very common on our beaches and washed 

 ashore by the gigantic Alga, "Laminaria," (kelp) which, being at- 

 tached to the shell, tears it from its bed, by the action of the 

 waves. Specimens are oftentimes of great size, and of consid- 

 erable beauty. 



Say's Am. Conchol., plate xlv. Blainville's Manuel, pi. Ixiv. 

 fig. 3. (A poor figure.) 



Cabinet of the Society. 



MODIOLA PLICATULA. Lamarck. A Latin diminutive, little 

 plicated. 



The common longitudinally grooved Muscle, beautifully pear- 

 ly within, and on the removal of the epidermis, having the same 

 pearly lustre without. Fixed by a silken cordage (byssus) to 

 piles, piers and wharves, and adhering to each other in similar 

 situations. Almost incredible stories are told in the British pub- 

 lications of the strength and tenacity of these shells, in preserv- 

 ing from destruction structures of wood and stone, from the vio- 

 lent action of the waves by means of the byssus. 



Cabinet of the Society. 



MYTILUS. Latin. JL kind of Muscle. 

 EDULIS. Latin. Eatable. Edible Muscle. 

 The common black or dark purple shell fish, so abundant on 

 our muddy shores, and considered a delicate article of food in 

 England, more than in this country ; against which a prejudice, 

 founded in part on facts, exists. At certain seasons of the year, 

 the animal feeds on the spawn of "The Five Finger/' (Asterias) 

 which renders it dangerous or at least suspicious ; instances of 

 3 



