THE ECONOMIC MOLLUSCA OF ACADIA. 
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16. Modiola plicatula Lamarck. 
Ribbed Mussel. 
[ Modiola , a little measure (?); plicatula , somewhat folded]. 
Distribution, (a) General ; — Between tides and in very 
shallow water. Georgia to Casco Bay, Maine. Gulf of St. 
Lawrence. 
(b) In Acadia ; — Not formally reported from the New 
Brunswick coast, but doubtless occurs upon the North Shore. 
North Shore of Nova Scotia, Jones (on authority of {Willis). 
Prince Edward Island, Dawson. Probably occurs all around 
the southern part of the Gulf of St. Lawrence and in Bras 
d’Or Lakes, and possibly in some part of Ohedabucto Bay. 
Habits. This species may easily be distinguished from the 
common or Horse-Mussel by the longitudinal foldings or ridges of its 
shell. These begin near the hinge and radiate to all the posterior part. 
FlO. 13. Modiola plicatula. Natural Size. 
It liyes in brackish water, preferring ditches and sluggish marsh 
streams. It partly burrows into the mud, well up towards high-water 
mark, and attaches itself by a strong byssus, or mass of threads. 
Economics. It is sometimes eaten, but is not considered 
as good as Mytilus edulis. It is a useful bait, but compara- 
tively little used, chiefly, no doubt, on account of its scarcity. 
It does not appear to be used for either of these purposes in 
Acadia, In New Jersey and about Long Island it is employed 
as a fertilizer, and in all probability it occasionally forms a 
small part of the “ Mussel-mud ” of our North Shore. 
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