THE ECONOMIC MOLLUSCA OF ACADIA. 83 



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 ol{Willis). 

 Prince Edward Island, Daivson. 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 Chedabucto Bay. 



Habits. This species may easily be distinguislied 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. 



Fig. 13. Modiola plicatula. Natural Size. 



It lives 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 eclulis. 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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