193 
shown on the same sheet with the curves of surface tempera- 
ture. 
The thermometers were in place too late, and for too short 
a period, to allow any safe conclusions to be based upon the 
information given by them, but it is noticeable, as an inter- 
esting coincidence, that the curves of both surface and bottom 
temperatures show the greatest variations about the time 
when the young were what is known as “ spat,” or during 
the period of, and just before, attachment, the young on the 
shoal beds presumably attaching by early August, and those 
on the deep water or southern beds somewhat later. 
I regret that it was impossible for me to more thoroughly 
study the effects of the change of temperature, as I think the 
failure or success of the spatting, other things being equal, 
will be found to depend mainly upon the temperature to which 
the mature oyster and embryos are exposed during the spawn- 
ing seasons. 
INVESTIGATION OF THE CHANGES IN DENSITY OF THE WATER. 
In order to have definite information as to the change of 
density of the water surrounding the oysters, and regarding 
such changes during the spatting season as of most import- 
ance, and as the maximum change would be most likely to 
occur about the time of the spring tides, I determined to ob- 
tain several specimens of water on a certain number of sec- 
tions across each Sound at high and low water of the spring 
tides. 
The sections were located as follows, and are shown on the 
sketches accompanying this report : 
Section Ho. 1 was just -above Hooper’s Straits and at the 
mouths of the Han ti coke and Wicomico Rivers, in order that 
the influence of both the straits and rivers might be shown. 
Section Ho. 2, for the same reason, was north of Hedge’s 
Straits and across the mouths of the Manokin and Big Anne- 
messex Rivers. 
Section Ho. 3 was across the entrance of both Sounds, south 
of Watts’ Island. 
13 
