THE ECONOMIC MOLLUSC A OE ACADIA. 
95 
large, Verkruzen. Mahone Bay, St. Margaret’s Bay, Sable 
Island, Willis. Sandy beaches, whole coast, Jones. Prince 
Edward Island, Dawson. Probably occurs in sandy situations 
where there is clear water around the whole coast of the three 
provinces. 
Habits. When fully grown this is the largest shell upon our coast. 
From the common Clam it is distinguished by its greater size and 
proportionall } 7 greater weight, as well as by its shape. Unlike the latter, 
its sides slope directly away from the hinge so as to give it a rounded- 
triangular shape. When young it is covered with a dull-brown or straw - 
FlGr. 17. — Mactra solidimma. Two-thirds of Natural Size, 
colored epidermis, which becomes mostly worn off in old specimens,, 
and is entirely absent in those cast up by the waves. Large specimens 
are six inches in length, but J. Matthew Jones mentions a specimen 
from Sable Island seven and one-fourth inches long and six and one- 
half in breadth, and Willis gives them even a larger size. 
It lives only in sand, and in situations where the water is clear. It 
burrows like the common Clam, but not deeply and does not form 
permanent burrows as does the latter. It is only uncovered at the 
lowest tides. 
Economics. It is used for food and is also put up for 
bait. Gould says it “is much esteemed by some as an article 
