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maximum number about the end of July, and decreases after- 
wards. 
The mortality after the 23d of August was very great, fully 
50 per cent, perishing from some unknown cause, which, 
though unknown, is certainly natural. 
We did not notice any evidence of the destructive effects of 
drills or other animals, though as their agency would only be 
discovered by the evidence of the holes in the upper valves, 
but as those valves were never present, it cannot be said with 
certainty that the destruction was not due to them. What- 
ever the cause, the fact is that 50 per cent, perished in the 
first six weeks of their existence. 
The tiles have shown that the increase in size is much 
greater than was supposed, and are the first and only authen- 
tic evidence upon that point which has been produced with 
regard to the American oyster. 
Again, it is conclusively shown by these tiles, and some 
others that were dredged up from the Woman’s Marsh Rocks 
(Hurdle Ho. 24), that the greatest attachment is on the lower 
concave side, and consequently that whatever may be the 
movements of the embryo oyster before attachment, during 
the period just prior to it, they are near, if not on the bot- 
tom, and in seeking their place of attachment they must rise. 
In this they are similar to the European variety. 
The selection of the lower sides of the tiles and the inte- 
rior of the “ boxes” may be an effort of nature to provide 
some protection for the young brood by, to a certain extent, 
inducing them to seek dark and secluded points for attach- 
ment, or the large number found in such places may be due 
to the inability of the various enemies of the spat to get at 
them when thus protected. 
It is a matter of very great regret that we have not a large 
number of specimens and observations for comparison, as all 
the future investigations in this field would be greatly assisted 
by an accurate knowledge of the rate of decrease in number 
and increase in size of the oysters, and it is to be hoped that 
the hurdle in the Big Annemessex will be allowed to remain 
