214 
BULLETIN OF THE BUREAU OF FISHERIES 
coast; but during the July and August cruise of 1914 we failed to find it at any 
station in the southeastern part of the basin, in the eastern and northern channels, 
on Georges or Browns banks, or near Cape Sable, indicating that at this season 
the C. Tiyperboreus of the Gulf of Maine are entirely cut off from the more northerly 
centers of abundance along the outer coast of Nova Scotia, though continuous with 
them and drawing from them by immigration earlier in the year (p. 217). During De- 
cember and January it occurred in the horizontal hauls in the western basin, off Penob- 
scot Bay, off Mount Desert Island, and in the Fundy Deep in 1920 and 1921 (table, 
p. 304); also at three stations off Gloucester in the winter of 1912-1913 (Bigelow, 
1914a, p. 409); and Willey (1921) records it in some abundance in the mouth of the 
St. Croix River from November to February during the winter of 1916-17, but not 
in January, 1920, though two specimens were noted in a tow taken on the 25th of 
March in that year. Unfortunately our November-January cruises have not 
extended to the offshore banks. 
Thus, the geographical range of C. Tiyperboreus in the gulf narrows from the 
sea shoreward in summer and expands offshore again at some time (just when remains 
to be discovered) during autumn or winter. 
Numerically C. Tiyperboreus is never more than a minor element in the plankton 
of the gulf, though its economic importance may be considerable because of its large 
size. Thus the average percentage of C. Tiyperboreus at the stations where it was 
detected in the vertical hauls was only about 4.5 per cent for March, 1920; 7 per 
cent for April, 1920; 2 to 3 per cent for all the May stations; and 7 per cent for all 
the June stations (see tables, pp. 297 and 299). In July, 1915, it averaged 2J4 per cent 
of three vertical hauls, and in 1913 about 1 per cent of two hauls (80 and 270 
Tiyperboreus to 8,800 and 5,400 jinmarchicus) . In 1912 there was 1 Tiyperboreus 
to 50 Jinmarchicus in a sample from one station (10023), and 6 Tiyperboreus among 
thousands of JinmarcTiicus in another (10040). On July 22, 1916 (station 10345) 
only one specimen was detected in a preliminary survey of some thousands of cope- 
pods and none at all at neighboring stations. Willey (1919), however, records 8 per 
cent of Tiyperboreus near Eastport in August. In December, 1920, and January, 
1921, it averaged 3.5 per cent at the stations where it occurred (table, p. 304) but only 
about 1 per cent at all the stations combined. The maximum abundance of C. 
Tiyperboreus is 45 per cent, but this is at a station where the total catch of copepods 
of all kinds was extremely scanty (7,500 copepods per square meter off Gloucester 
on April 9, 1920, station 20090). The vertical hauls for 1915 and 1920 afford only 
eight instances of Tiyperboreus in percentages as great as 15 per cent. 
The numbers per square meter— counting only the stations at which it 
occurred — are as follows: 
Date 
Average 
Maximum 
Minimum 
February, 1920 
683 
1,125 
25 
March, 1920 
403 
4, 162 
0 
April, 1920 
804 
9,100 
20, 575 
6, 450 
0 
May, 1915, and May, 1920 - 
2,561 
1,634 
0 
June, 1915 
25 
