ANOMIA. 203 



Ostrea borealis. 



Shell somewhat rounded, curved, scaly, greenish ; beaks rather short, consid- 

 erably curved; hinge having the furrow in the lower valve from the apex, but 

 having in the opposite valve merely a transverse ridge, not extended back- 

 wards. 



Ostrea borealis, Lam. An. sans Vert. vii. 220. — Gould, Invert. 1st eel. 137. — De Kay, 



N. Y. Moll. 169, pi. 10, fig. 203, 204. — Stimpson, Shells of New England, 8. 

 Odrea Canadensis, BuuG. Encyc. Me'th. pi. 180, figs. 1 -3. — Lam. An. sans Vert. vii. 226. 

 Ostrea edulis, Lin., &c. 



Shell somewhat obliquely rounded ovate, usually curved, upper 

 valve smaller, flatter ; the beaks are never greatly prolonged, more 

 curved than in O. Virginiana. The surface is very irregular, dis- 

 playing loosely arranged flakes of a greenish-color ; the margins are 

 generally more or less plaited or scalloped, entirely bony in the 

 lower valve, but membranous and somewhat flexible in the upper 

 one. The hinge differs from the preceding in having the beaks less 

 prolonged, and the upper valve, instead of having a lengthened, 

 pyramidal ridge extending backwards to the apex, has only a trans- 

 verse ridge, abrupt behind, and sloping into the shell, like a mere 

 partition, behind which the cartilage is attached. The muscular 

 impression is also dark violet. Interior, either chalky or greenish- 

 white. 



This species also grows to a great size. A specimen before me 

 measures a foot in length, and six inches in breadth. A common 

 size is five and six inches in length. 



This is the common New York oyster, and, although they are said 

 to have been once abundant in various parts of Massachusetts Bay, 

 especially within Cape Cod, yet the Boston market is now chiefly 

 dependent for its supply on the oyster-beds in the vicinity of New 

 York, and in the Chesapeake. In those parts of Buzzard's Bay 

 which border upon Sandwich the native oyster is still found in 

 great abundance. 



The oystermen maintain that our shell is identical with the Eng- 

 lisli O. edulis ; and there are certainly forms in wliich the American 

 and European specimens could not be distinguished. 



Oenus A^OITIIA, Lam 1767. 



Shell irregular, inequivalve, one valve convex, the other flattened 

 or concave, perforated near the beak for the passage of a muscle, 

 by which it adheres. 



