394 BULLETIN OF THE BUREAU OF FISHERIES', 



as was the case at our outermost stations in the summer of 1914 (stations 10218 

 and 10220). July and August stations (10218 and 10261) in 1914 over the slope 

 west of longitude 68° W. and south of latitude 42° 10' N. likewise yielded small 

 amounts of the characteristically tropical alga Trichodesmium, together with 

 Ceratium macroceras, which also occurred off the southeast face of Georges Bank 

 in July (station 10220) and in the coastal waters off Martha Vineyard in August 

 (stations 10258 to 10260) ; but we have never found C. macroceras along the conti- 

 nental slope farther east than the Eastern Channel. 



Although tropical pelagic plants, both large and miscroscopic, as well as plank- 

 tonic animals belonging to this same category in their relationship to temperature, 

 may be expected to encroach on the western half of Georges Bank at some time during 

 most summers, just as they do more regularly and abundantly farther west and 

 south, the exact season when this happens varies considerably from year to year, as 

 might be expected from the fluctuations in the location of the inner edge of the 

 Gulf Stream, a fact illustrated by their failure to appear there by the third week of 

 July in 1916. Probably they are hardly to be expected along Georges Bank earlier 

 than the first of that month, even in warm years, and are locally more characteristic 

 of the months of August and September. 



Autumnal data on the phytoplankton of the gulf outside the Bay of Fundy are 

 limited to a series of stations covering its northern half for September, 1915, and to 

 occasional October and November hauls between Cape Cod and the Grand Manan 

 Channel during the years 1912, 1915, and 1916. Bailey (1910 and 1917) and Fritz 

 (1921) have also published lists of diatoms from St. Andrews and neighboring parts 

 of the Bay of Fundy, for the autumn as well as for other seasons of the year, and 

 Doctor McMurrich's plankton lists include the status of several genera of diatoms and 

 of peridinians at St. Andrews in autumn. These records, united, show that diatoms 

 practically disappear from the deeper parts of the gulf — not, however, from the 

 Bay of Fundy — after the last days of August, leaving almost its entire area outside 

 the outer headlands occupied by a Ceratium community, with the Mount Desert 

 and Massachusetts Bay regions and the Bay of Fundy alone supporting diatoms in 

 appreciable number. In fact, we have never found abundant diatom plankton 

 anywhere else in the open gulf, either in September or in October, though diatoms 

 were present in some numbers, together with the peridinians, along shore from 

 Penobscot Bay to the Bay of Fundy up until the 9th of October in 1915, and 

 dominated the phytoplankton near Mount Desert Island on that day (station 10328). 



Considerable catches of diatoms at the mouth of Massachusetts Bay during 

 the last week of September, 1915, resulted from a rich flowering of Skeletonema. 

 This genus is comparatively rare there in spring (p. 44S), but in the summer of 1922 

 it had commenced flowering in the coastwise belt and among the islands along the 

 northern shore of the bay by August, and the three successive states — spring, August, 

 and September — though for different years, suggest that its normal cycle is to 

 spread offshore as the season advances. Its flowering period was apparently brief 

 in 1915, however, and probably is in most years, having come to an end before 

 October 26 or 27, by which date its place had been taken once more by Ceratium, 

 with only occasional diatoms (Coscinodiscus and Thalassiothrix longissirna) in the 



