PLANKTON OF THE GULF OF MAINE 
413 
Relative numbers of C. tripos and C. longipes in samples 
General locality and date 
Off Isles of Shoals: 
Aug. 5, 1913, station 10105. . 
Nov. 1, 1916, station 10400. 
Off Cape Elizabeth: 
Aug. 14, 1913, station 10103. 
Aug. 14, 1914, station 10251. 
Sept. 20, 1915, station 10319. 
Off Penobscot Bay: 
Aug. 14, 1914, station 10250- 
Sept. 16, 1915, station 10318. 
Oct. 9, 1915, station 10329.. 
C. lon- 
gipes 
C. tripos 
General locality and date 
C. lon- 
gipes 
C. tripos 
Near Mount Desert Island: 
« 
0) 
Aug. 13, 1913, station 10099 
(>> 
(■) 
i 
3 
Aug. 18, 1915, station 10305 
20+ 
1 
Sept. 15, 1915, station 10317 
13 
3 
40 
18 
Oct. 9, 1915, station 10328 
( ! ) 
( 4 ) 
115 
1 
Off Machias, Me.: 
( ! ) 
( 3 ) 
Aug. 13, 1913, station 10098... 
26 
7 
Aug. 12, 1914, station 10247.. 
42 
3 
32 
2 
Sept. 11, 1915, station 10316 
9 
25 
13 
5 
Oct. 9, 1915, station 10327... 
( 2 ) 
0 
8 
5 
1 Numbers about equal. 2 Predominant. 3 Fewer. 4 Not found. 
Just how rapidly C. tripos may be expected to spread eastward toward Cape Sable 
from its offshore center of abundance in the center of the gulf is yet to be learned. 
It is established, however, that on August 12, 1913 (station 10095), and again on 
September 2, 1915 (station 10311), the two species were present in roughly equal 
numbers on German Bank, where longipes alone was found in June, 1915 (station 
10290). Tripos greatly outnumbered longipes near Lurcher Shoal (station 10245) 
and in the neighboring part of the basin (station 10246) as early as August 12 in 1914. 
It is also probable that tripos will usually be found to dominate close in along the 
west Nova Scotian coast before the middle of September, for it outnumbered longipes 
near land off Shelburne (a few miles east of Cape Sable) on the 6th of that month in 
1915 (station 10313, 30 tripos to 12 longipes), where we had found longipes predomi- 
nant the previous June, 40 as well as during July and August of 1914. 41 
Ceratium tripos comes finally and definitely to dominate over C. longipes in all 
parts of the gulf by the middle or end of October, including even the coastal belt east 
of Penobscot Bay. McMurrich (1917) did not find longipes at all at St. Andrews 
after the 16th of that month, whereas C. tripos occurred there regularly from that 
date until March 2, when Ceratium disappeared with the inception of the vernal 
flowering of diatoms. 
C. tripos has greatly outnumbered C. longipes in all the parts of the gulf we have 
visited in midwinter; in fact, the latter, if not wanting, was at least so rare that I 
failed to find it in several of the samples examined. 
Relative abundance of the several species of Ceratium in winter, from samples 
Locality 
C. lon- 
gipes 
C. tripos 
C. fusus 
C. arcti- 
cum 
Massachusetts Bay, Dec. 29, 1920, station 10488. 
1 
19 
2 
2 
Off Cape Ann, Dec. 29, 1920, station 10489. 
1 
20 
1 
0 
Western Basin, Dec. 29, 1920, station 10490 
0 
50 
2 
0 
Off Cape Cod, Dec. 30, 1920, station 10491 
2 
30 
3 
0 
Off Merrimac River, Dec. 30, 1920, station 10492 
1 
18 
1 
0 
Off Isles of Shoals, Dec. 30, 1920, station 10493 
0 
15 
3 
1 
Off Cape Elizabeth, Dec. 30, 1920, station 10494. 
0 
15 
3 
X 
Off Penobscot Bay, Jan. 1, 1921, station 10496 
1 
40 
2 
0 
Off Mount Desert Island, Jan. 1, 1921, station 10497 
2 
35 
4 
3 
Off Machias, Me., Jan. 4, 1921, station 10498 
1 
15 
1 
0 
Fundy Deep, Jan. 4, 1921, station 10499 
1 
52 
7 
0 
Eastern Basin, Jan. 4, 1921, station 10500 
3 
20 
13 
0 
Eastern Basin, Jan. 5, 1921, station 10502 
7 
43 
1 
0 
Off Yarmouth, Nova Scotia, Jan. 4, 1921, station 10501. 
1 
19 
2 
o 
40 Station 10291, 19 longipes, 1 tripos; station 10294, many longipes and intermediates between it and arctica, no tripos. 
41 Station 10232, July 28, many longipes, no tripos; station 10233, July 28, 42 longipes, 3 tripos; station 10243, August 11, many 
longipes, no tripos. 
8951—28 27 
