THE ECONOMIC MOLLUSCA OF ACADIA. 47 



John, Picton, Tracadie, Mabou, Margarie, Sydney, Albert 

 Bridge, County Harbor,* St. Mary's River*, Liscombe Harbor*, 

 Jeddore Head,* and nearly every where in the Bras d'or Lakes. 

 (In P. E, I.) All aronnd the coast in favorable situations. 



Habits. A species, with a range as great as this, and one found 

 under such diverse conditions, must necessarily present great variations. 

 It vrould be impossible to give of it a description, either scientilic or 

 popular, which would apply to all of its individuals. Sometimes round 

 in outline, sometimes nearly as elongated as the Razor-shell, and with 

 every gradation between these extremes, presenting every possible 

 variation as to convexity and corrugation of the valves, it must be con- 

 sidered the most variable bivalve of our coasts. Many of these varia- 

 tions are due to modes of attachment, overcrowding and other conditions 

 to be considered below, but others depend upon conditions not yet 

 understood, particularly those cases in which a certain general form is 

 characteristic of a special locality. 



The Oyster f is a bivalve, as everybody knows, with a hinge of 

 simple mechanism at one end, so arranged as to tend to keep the shell 

 constantly a little open. This is its position when lying undisturbed on 

 the bottom, when weakened, or when dead. But the living animal has 

 the power of closing the valves and keeping them closed by means of the 

 single powerful muscle, the position of which is marked by the purple 

 scars, known as the " eje," on the interior of the two valves. The 

 entire interior of each valve has a rather thick, dark-edged, fringed 

 membranous lining called the mantle, which, when full}' extended, is a 

 little larger than the valve and extends like a fringe beyond it. It is 

 this mantle which builds the shell. That of one valve is not connected 

 with that of the other except at the hinge and at one other point near the 

 opposite end. Thus the animal is open or exposed nearly all around 

 and not closed in as it would be if the mantle were almost continuous 

 as in the Clam. 



Of the two valves, one is usually flat and the other convex. The latter 

 is the under one as the animal lies undisturbed on the bottom, and in its 

 hollow, as in a dish, lie the other organs. The hinge is at the extreme 

 anterior end, differing thus from the Clam in which it lies near the back 

 of the animal. Inside the mantle, and just behind the hinge is the 



♦Given by lugersoll in U. S. 10th Census, "Oyster Fishery," on authority of 

 Piirdy. 



tAs would be expected from its great economic importance, the structure and 

 habits of the Oyster have been very thoroughly studied, and its Ufe history is now 

 as well known as that of any Mollusc. Those who are specially interested will find 

 the subject very fully treated in the works quoted at the end of this article, some of 

 which ari easily accessible. 



