478 THE POPULAR SCIENCE MONTHLY. 



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 spe- 

 cial 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 an- 

 nual 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 mol- 

 lusk can grow. When oysters are excessively crowded they will grow 

 standing on end, that is, side by side, with the nib or wide end upper- 

 most, 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 oblit- 

 erated, 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 quar- 

 ter 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 tradi- 

 tion 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 



