Economic mollusca of Acadia economicmollusca00gano Year: 1889 THE ECONOMIC MOLLUSCA OF ACADIA. 71 the sea-shore must know it well. There is only one common Mollusc at .all likely to be mistaken for itâand that is the Horse-mussel, Modiola modiolus. But the former is blue-black generally, and the latter is -chestnut, or rather its epidermis is, and their situations or habitats are different, as will be seen by reading the descriptions of both. A good mark to separate them is found in the position of the umbo, or raised Tinob around which the concentric lines of growth of the shell are arrange
Economic mollusca of Acadia economicmollusca00gano Year: 1889 THE ECONOMIC MOLLUSCA OF ACADIA. 71 the sea-shore must know it well. There is only one common Mollusc at .all likely to be mistaken for itâand that is the Horse-mussel, Modiola modiolus. But the former is blue-black generally, and the latter is -chestnut, or rather its epidermis is, and their situations or habitats are different, as will be seen by reading the descriptions of both. A good mark to separate them is found in the position of the umbo, or raised Tinob around which the concentric lines of growth of the shell are arranged; this is at the extreme end in J/. ednJis, but set a little back near one margin in Modiola modiolus. Its lack of raised ribs distinguishes it from M. plicahda. This species varies somewhat in color, the variant individuals being of a darker or lighter horn-color, and generally showing radiating, longitudinal, dark lines. These forms are by some considered to form a â distinct varietyâto which the name pellucidiis is given. Within, the Fig. 11. âMytibus edulis. Natural Size. «hell is dark-yiolet, silver and while, and often very beautiful. The average length of adults is about three inches, though they grow as great as five, and even over eight inches in rare cases in Europe. They vary greatly in outline, the nature of the variation of an individual depending â chiefly upon the conditions under which it has grown. It is a fact of no little importance to man, as will be presently seen, that the edible Mussels are gregarious. All visitors to the shore remember well the great beds, often acres in extent, which are found on the flats, â¢especially of estuaries. They never burrow, but instead, fix themselves by means of a mass of silky threads which are secreted by the foot and pass out between the valves. With these they can attach themselves to any surface, sand, mud and gravel, rocks, piles of wharves, buoys, bottoms of boats, and, in fact almost anywhere. They pre
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