Page:Popular Science Monthly Volume 20.djvu/494

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one seven inches long and three and a half wide, the other seven and a half inches long and four inches wide. The shells are quite heavy, and for their size the oysters are not so large as might be inferred; but they were eaten, and the verdict was that one was good and the other fair. As this was the judgment of an oyster-raiser, it had special value. The age of an oyster may be reckoned by counting the lines in the depression or groove of the hinge of the bivalve. These lines truly indicate the layers or annual shell-growths, being really the anterior extremity of the annual shell deposits. But the lower shell of an oyster, that is, the valve in which the animal lies when the shell is in normal position, is the deeper and heavier of the two, and, as its annual shell-layers correspond in number with those of the upper valve, it follows that they must be proportionally thicker. Hence the result is that the hinge-groove of the lower valve is longer than that of the upper valve, because the lines which are the extreme edges of the layers are thicker than the lines in the upper groove. Wherever the oyster has room and fair conditions this is the necessary law of its growth, viz., for gravity's sake the ponderosity is given to the lower valve; also for the comfort and growth of the animal, as it secures it a normal position and the proper trough or cradle in which the mollusk can grow. When oysters are excessively crowded they will grow standing on end, that is, side by side, with the nib or wide end uppermost, thus producing those worthless, elongated forms known in some localities as "strap-oysters" and "stick-ups."

Being interested in these specimens as uniques, to me at least, I was concerned to see if the natural record would tally with the well authenticated tradition of their age. To shorten the story, I will give the method of examination of but one of them. In this instance the distal end, that is, the oldest parts of the hinge-grooves, were coated with the skeletons of bryozoa, hence the line-record was partly obliterated, so that a clear count could only be got from the near end of the groove. Fortunately, the lines were so uniform in thickness that the estimation was reduced to a simple question of proportion. By actual measurement the length of the upper groove was one and a half inch, and that of the lower one was two and a half inches. Now, in the upper groove there were five of these annual layer-lines in a quarter of an inch, and in the lower groove there were, as nearly as I could make out, three lines and a third of a line in a quarter of an inch, which would give thirty of these annual lines for the upper groove and thirty in the lower groove, all which would tally with the tradition that the bivalve was thirty years old.

Two points are established by the above: first, the great longevity of the oyster; the specimens were in excellent condition, and there was nothing about them to disprove the belief that, if allowed to lie undisturbed, they might have lived and grown ten years longer; and second, that an oyster may be good and palatable food at a great