PLANKTON OF THE GULF OF MAINE 289 



and over the deep trough within the Gulf of St. Lawrence (Willey, 1919), and its 

 range extends far out into the ocean off Labrador, as just noted (p. 287). 



Seasonal distribution. — McMurrich (1917) has remarked that Temora occurred 

 at intervals at St. Andrews during the autumn of 1914 and up until January 27, 

 1915 (on which date it was the dominant component of the plankton), but not at 

 all from February to mid-May. His unpublished plankton lists for November, 1915, 

 to October, 1916, carry the observations a step farther, showing Temora constantly 

 present at St. Andrews, and in considerable numbers, from mid-September through 

 January, but only at intervals, and represented by odd individuals, during the other 

 months. Wheeler (1901) and Fish (1925) have likewise found it much more plentiful 

 at Woods Hole in winter than in summer. 55 



Temora longicomw has been recorded in the open waters of the Gulf of Maine 

 in every month in the year except November and February, when few tows have 

 been studied for their copepods. In the coastwise belt the frequency of occurrence 

 has been highest during the period September to January, and again from March to 

 April, as indicated by the percentage of stations at which it occurred (about 50 per 

 cent in each case), and lowest during the June-August quarter, when it was recorded 

 at only 22 per cent of the stations in this region. However, this may reflect an 

 annual and not a seasonal fluctuation, because Temora occurred in a much larger 

 percentage of our hauls in July and August of 1913 (about 50 per cent in the gulf, 

 on Georges Bank, and off Nantucket) than in those months in 1912. It was again 

 scarce in the summer of 1914 (14 per cent of the stations on Georges Bank and in 

 the gulf; not at any of the stations off Marthas Vineyard); but the year 1915, when 

 Temora occurred at about 42 per cent of the stations right through the season from 

 May to October, apparently saw the local stock increase once more. The percentage 

 of occurrence has been about the same (33 to 38 per cent of the stations) for July- 

 August as for February-May on the offshore banks and over the shelf off Nantucket 

 and Marthas Vineyard. 



In short, such analysis as I have been able to make does not prove a definite 

 periodicity in the frequency of this species in the open gulf beyond suggesting the 

 possibility that there is a minimum in midsummer. 



The evidence of the vertical hauls (tables, pp. 297 and 299) is that Temora is 

 seldom if ever dominant anywhere in the open gulf at any time, for at the maximum 

 it has constituted only 20 per cent of the catch of copepods (station 20062) ; 5a and 

 in only six of the many vertical hauls anywhere between the longitudes of Marthas 

 Vineyard and Cape Sable has it constituted as much as 10 per cent of the copepods, 

 the average for all being only about 3 to 4 per cent of Temora, even if the calculation 

 be limited to those stations where this copepod was plentiful enough to be picked up 

 by the vertical net. If the stations where it was missed be included; its average 

 percentage drops below 2 per cent. The absolute numbers of individuals per square 

 meter have been correspondingly insignificant, compared to those of Calanus fin- 

 marchicus, at the maximum being only about 18,000 within the gulf, 18,760 off Shel- 

 burne, Nova Scotia (station 10313, September 6, 1915), and about 33,000 near Marthas 



" Williams (1907) reported it as abundant throughout the year In Narragansett Bay. 

 •• 28 per cent off Shelburne, Nova Scotia, Sept. 6, 1915, Station 10313. 



