THE ECONOMIC MOLLUSCA OF ACADIA. 
89 
is evidently common in the Gulf of St. Lawrence, from Bay 
Chaleur to Cape Breton. It seems strange, however, that it 
should be reported as being common all around the coast of 
Nova Scotia, when it is totally unknown upon the Bay of 
Fundy coast of New Brunswick. It is probably to be found 
wherever the Oyster lives, and being somewhat more hardy, 
occurs rather beyond those limits. 
Habits. This species is well-known to all oystermen and frequen- 
ters of fish-markets. It is a bivalve shell, having two very thick and 
heavy valves of a dingy white or ash color. Upon these are well 
Fig. It. — Venus mercenary a. Natural Size. 
marked, very regular, concentric folds, which become quite sharp where 
not wan by friction. Inside they are chalky white, except at the 
smaller end, where they are usually of a beautiful purple. The margin 
is finely crenulated around three-fourths of its circumference. The 
shell is roughly heart-shaped in outline, about three and one-half inches 
long when full grown, and two and three-quarter inches high. These 
characters will distinguish it from any other form found upon our 
coast. The purple color is wanting in young shells, quite variable in 
amount in others, and is often covered by a thick white glazing in very 
old ones, while in certain cases it is wanting altogether. 
Of its mode of life, Prof. Yerrill says, — “ Common on sandy shores > 
living chiefly on the sandy and muddy flats, just beyond low-water 
mark, but is often found on the portion laid bare at low water of spring 
