173 
habitants ; an increased percentage means a decreased popula- 
tion. 
It is evident that there should be a certain proportion be 
Iween the oysters of different ages, and in general terms the 
number of young should exceed the mature, thus allowing for 
the natural depletion in each period of growth. 
Our present knowledge, however, is not sufficient to allow 
the assignment of exact values to these proportions, and the 
ratios between the different classes are too irregular, owing 
to the variations in the spawnings in the several seasons, to 
allow their acceptance as a standard. 
One thing, however, may be assumed as an axiom, and that 
is that the number of young growth on a bed should always 
•exceed the mature oysters, for if there are no young oysters 
in the community there will soon be no old ones, and as there 
is a constant depletion of each class, the young must suffi- 
ciently outnumber the old ones to allow these ravages and 
still adequately supply the demand and fill up the vacant 
places in the higher classes. 
An inspection of Table 1 will show — 
1st. That 0.75 per cent, of the 4th class were of this year’s 
growth. 
2d. That the ratios between the 3d and 4th classes are the 
largest, and between the 2d and 3d classes the smallest. 
As the 2d class represents oysters of between two and three 
years of age, and, as the ratio between the 2d and 1st classes 
is large, I judge that there was a successful spatting on these 
beds in 1876; and as the 3d class represent, on the whple, 
oysters of the season of 1877 and 1878, and as the proportion 
between those of that class and those of the second is small, 
I infer that the seasons of 1877-78 were bad spawning ones. 
Again, the 4th ciass are principally of this year’s growth, 
and the ratio of 4th to 3d class is large, from which I infer 
what was the case, that the spatting of the last season on 
these beds was successful. 
As already explained, the 3d and 4th classes practically rep- 
resent the offspring of three successive spatting seasons, and 
thus contain the young growth on the bed, while the 1st and 
