338 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Thus the only part of the Gulf where volume, or number of copepods, 
or both, was greatest in 1912 was off Massachusetts Bay, and near 
Cape Elizabeth and Platt’s Bank; a difference which may be seasonal. 
Everywhere else both the volume of plankton and the number of 
copepods was greater in 1913 than in 1912. It is possible that locations 
close to shore might have proved an exception; but judging from what 
was found east of Mt. Desert and on German Bank, there is no rea- 
son to suppose that shore stations would have altered the case materi- 
ally. On the average, the hauls for the whole Gulf were nearly twice 
as large in bulk, and 60% larger in number of copepods, in 1913; a — 
difference so great that it can hardly be accidental, especially as the 
same net was used in both years. In short, there seems no escape 
from the conclusion that both the plankton as a whole, and its-copepod 
constituent, were richer in August, 1913, than in the summer of 1912. 
Very little can be said about the microplankton of the two years 
until the microscopic examination of the hauls is completed. But 
enough has been done to show that diatoms were far less numerous 
in August, 1913, than in the corresponding month of 1912. And the 
species which formed the bulk of the catch in that year, Asterionella 
japonica, has not been detected at all in the 1913 hauls. Furthermore 
the Ceratium plankton was nowhere so dense in 1913 as off Cape 
Elizabeth in 1912. | 
MACROPLANKTON OF THE GULF OF MAINE AND OF THE NORTHEASTERN 
ATLANTIC. 
Our survey of the plankton of the Gulf of Maine in 1912 led to the 
conclusion that it was characteristically boreal, in the sense in which 
the term is used by Hjort (Murray and Hort, 1912, p. 637), not Arctic, 
though with Arctic and Gulf Stream components (1914a, p. 106). 
And subsequent catches support this general thesis. 'The most im- 
portant member of the plankton of the Gulf, Calanus finmarchicus, 
it is true, is practically eurythermal, but it is only in boreal, and in 
Arctic-boreal waters that it swarms (Farran, 1911) and it is not dis- 
tinctive of polar water, although it is very numerous and very large 
in the Labrador Current (Herdman, Thompson, and Scott, 1898). 
On our coasts Calanus plankton apparently occupies an unbroken 
belt from the Labrador Current to Cape Cod. The only copepod 
which vies with it in abundance in the Gulf, Pseudocalanus elongatus, 
is likewise chiefly boreal, not polar, and far more plentiful in coastal 
