PLANKTON OF THE GULF OF MAINE 
411 
expected to dominate the plankton in different regions, by our experience, are laid 
down on the chart (fig. 110). Our records show that it outnumbers or replaces 
C. longipes first in the offshore parts of the gulf, and that it may be expected to pre- 
dominate over the latter in the western and central deeps and in the eastern branch 
of the basin north to latitude 43° or 43° 30' N. by mid-August. 
The following counts of samples from corresponding pairs of stations illustrate 
how completely the relative importance of the two species is reversed between June 
or the first half of July and the first days of August, and how nearly to the vanishing 
point C. longipes sinks in these particular parts of the gulf as C. tripos multiplies. 
General locality 
Relative numbers 
in samples 
C. 
longipes 
c. 
tripos 
100-meter curve, off Cape Cod: 
43 
15 
Aug. 5, 1913, station 10086 
5 
60 
50-meter curve, northeast of Cape Cod: 
50 
1 
Aug. 28, 1914, station 10264. 
1 
23 
Southwest part of deep basin: 
July 19, 1914, station 10214 
63 
3 
5 
76 
Western Basin, off Cape Ann: 
19 
4 
Aug. 31, 1915, station 10307 
1 
50+ 
Eastern Basin, lat. 43° 17': 
13 
47 
Eastern Basin, lat. 43° 08': 
4 
28 
A corresponding preponderance of tripos (32 to 2 longipes) likewise characterized 
a haul made by Capt. John McFarland off Chatham (Cape Cod) on August 26, 
1913. 39 
The multiplication of or intrusion by C. tripos is apparently a slower process, 
and C. longipes persists correspondingly longer as an important factor in the plankton 
over the northeastern part of the basin. Thus in mid-August of 1914, when tripos 
already greatly predominated right across the gulf along a line from Cape Ann to 
Cape Sable, C. longipes still outnumbered it a few miles to the northward, as follows: 
Number in samples 
Locality 
C. 
longipes 
c. 
tripos 
Off Lurcher Shoal Aug. 12, 1914, station 10245 
105 
1 
Extreme northeast corner of basin, Aug. 12, 1914, station 10246 
62 
1 
Off Mount, Desert Rock, Aug. 13, 1914, station 10248 
29 
1 
Off Penobscot Bay, Aug. 14, 1914, station 10250 
32 
2 
Off Cape Elizabeth, Aug. 14, 1914, station 10251 
115 
1 
In 1913 longipes still continued about as numerous as tripos in the deep hauls 
in the eastern side of the gulf (latitude about 43° 25' N., stations 10092 and 10093) 
on August 11 and 12, by which date tripos was already predominant in the western 
basin (stations 10088 and 10089). 
39 In the report on the cruise of 1912 the two species were listed together as tripos (Bigelow, 1914). 
