OYSTER AND MUSSEL REPORT. sal 
was certainly very warm. When run from the seawater 
taps in the Zoological Station I found it was at 74°F. with 
a specific gravity of 1°023, out in the middle of the 
“bassin”? I found it at 76°F. with a specific gravity of 
1:024, while over the shallow oyster parcs I found it 
varying from 78°F’. to 80°F. with a specific gravity of 1:022 
to 1024, and in one or two corners of the parcs at low 
tide where the last of the ebb had been exposed to the 
midday sun it rose as high as nearly 90°F. 
The cultivators at Arcachon are of opinion that the 
oysters could not be bred successfully, that there would 
not be a sufficient deposit of spat, in waters that are much 
cooler, but we have evidence to the contrary in what Captain 
Dannevig says in regard to the plentiful spawning of the 
oyster in his pond at Norway, and also in the deposits of 
spat on the North Coast of France and South Coast of 
England. The temperature in July in Dannevig’s pond at 
Arendal was about 63°F.; while at Port Erin, Isle of Man, 
the temperature in the bay during the first week in July 
varied from 59° to 62° F., and on July 22nd was 59°F. 
with a specific gravity of 1025, and shore pools near the 
Biological Station, fairly comparable with the oyster pares 
at Arcachon, ranged in temperature on July 22nd from 
59°F. to 76°F ., and on July 13th from 60° to 76°F. 
I am very hopeful that although the specially high tem- 
perature of the ‘‘ bassin”’ at Arcachon—and possibly stil 
more the calm weather during the critical period when the 
young animal is free-swimming and then settling down 
for life—may have favoured an unusually heavy deposit 
of spat, still no such great heat is really necessary for a 
normal amount of reproduction and development, and that 
we may have in our neighbourhood water sufficiently 
warm for the purpose. 
As to the specific gravity : —it varies at Arcachon from 
