[PRINCE] BIOLOGICAL INVESTIGATION OF CANADIAN WATERS 78 
Significance of the Oyster Distribution. 
The presence and absence of the oyster (Ostrea virginica), in 
certain localities, depend, we know, upon many delicate and somewhat 
inappreciable conditions, hence its apparently erratic distribution, and 
absence from most of the Nova Scotia shore and the New Brunswick side 
of the Bay of Fundy, over most of which coast line the Acadian fauna 
is recognized. Schmitt is inclined to attribute the stunted character of 
so many Gulf species, at any rate those along the north or Quebec shore, 
as due possibly to lack of food in the water “ Ce nansime,” he says, “ est 
peut-étre en partie par la rareté de la nourriture résultant du peu de 
matiéres organiques en suspension et par le milieu relativement froid ot 
Vanimal ne trouve pas son optimum de croissance.” The field of 
biological investigation is thus not merely remarkable for its geographi- 
cal extent but for the complex and profoundly interesting factors, 
physical, chemical, ete., which determine its faunistic features. 
Comparison of North Sea and Gulf of St. Lawrence. 
Now, we know that such a body of water as the North Sea which 
is very shallow and includes a number of banks, famous as fishing 
grounds, has a low bottom temperature, indeed a great part of its floor, 
especially towards the north is covered with a stratum of cold water. 
This cold stratum is traced to the Polar current, while above this is the 
warmer inflow of the Atlantic current, still retaining something of the 
Gulf Stream infiuence. But the average depth of the North Sea is less 
than one hundred fathoms, over a great part of the one hundred and 
forty thousand square miles constituting its area; shallowing most 
markedly, moreover, towards its southerly margin. 
The northern portions range from 160 to 300 and 400 fathoms, 
and still further north, deepen into the watery abyss of the Norwegian 
Sea, which shows 2,000 fathoms. 
The famous fishing banks are much scattered; but the principal, 
the Dogger, les about seventy miles directly east of Flamborough 
Head, Yorks, and runs north-easterly for 150 miles, being sixty miles 
across at its greatest breadth. The depth is only seven to twenty-four 
fathoms, deepening towards the north-east, and at the Great Fisher 
Bank increasing to forty-five and fifty fathoms. Off its southwest 
extremity: are the Silver Pits,—-a fishing bank sixty miles long,—and 
the depth is there twenty-five to fifty fathoms. Southeast of the Dogger 
are Cromer Knowle, twelve to eighteen fathoms deep, and the Leman 
and Dowsing Banks. 
