PLANKTON OP THE GULF OF MAINE 
455 
western side of the gulf during April, 1920, nor did Fritz find it at St. Andrews at 
any time during the spring or until the end of August. But it occurred sparingly 
at two of our April stations in the northeast corner of the gulf and off the Nova 
Scotian coast (stations 20101 and 20103), likewise locally off Georges Bank (station 
20109), in the basin (stations 20114 and 20115), and off Cape Cod (station 20116) 
during that month in 1920. We have twice made rich catches of Thalassiothrix 
between Cape Elizabeth and Penobscot Bay in May (station 10277, May 13, and 
station 10280, May 31, 1915). It likewise dominated the diatom plankton on the 
western end of Georges Bank and southeast of Nantucket Shoals on July 23, 1916 
(stations 10347, 10348, and 10354), but we have not found it elsewhere in the open 
gulf during June, July, or the first half of August, though Fritz (1921) records it at 
St. Andrews on August 28. 
Th. longissima was present in small numbers off Penobscot Bay on September 
15, 1915 (station 10317), and irregularly at St. Andrews during that month in 1917, 
according to Fritz. It flowers abundantly in the Bay of Fundy and along the coast 
of Maine in October, for Fritz counted over half a million in her standard haul at 
St. Andrews on October 6, 1917. It was abundant near Mount Desert Island on 
October 9, 1915 (station 10328), and a corresponding augmentation of this species 
extended southward at least as far as Cape A nn during the last 10 days of that 
month (stations 10329 and 10330). 
Fritz found few Th. longissima at St. Andrews after the middle of October and 
none in January or February. Neither have we found it anywhere in the open gulf 
during the winter. McMurrich (1917) describes it as present in great numbers at 
St. Andrews on February 26, 1915. 
On the whole these data suggest two maxima for Th. longissima — one late in the 
spring and the other in October, 72 paralleling its seasonal history in the North Sea 
region, where its chief flowering time is May, though it may also occur in great 
quantities around Scotland in August and November (Ostenfeld, 1913, p. 408). 
At Woods Hole Fish (1925) found it regularly in late winter and spring but only 
occasionally at other seasons. The flowerings of Thalassiothrix observed by Mc- 
Murrich in February and March show that its seasonal cycle is less regular than 
that of Thalassiosira, Biddulphia, etc. 
TJi. longissima is usually a minor element in the phytoplankton of the inner parts 
of the gulf, where its flowerings are not only local but brief in duration. But it was 
extremely plentiful on the western end of Georges Bank on July 23, 1916, at the 
stations just mentioned, where with fewer Rhizosolenia styliformis it formed a very 
rich and monotonous diatom community (fig. 124) , and when its center of abundance 
extended over a considerable area, out to the continental slope on the south and to 
Nantucket Shoals on the west. 
We have never seen this flowering of Thalassiothrix rivaled within the gulf, 
and a single occurrence of this sort does not necessarily establish Georges Bank as a 
major center of production for it. This species is so large and so easily recognized 
that it may finally prove of great value for the study of ocean currents, as Ostenfeld 
12 Probably the “Thalassema” mentioned by Bailey (1917, p. 107) as dominating some of the October gatherings in Passama - 
quoddy Bay were actually Thalassiotkriz longissima. 
