440 BULLETIN OF THE BUKEAU OF FISHEKIES 



and 10492 to 10497). We have occasional records of it in March (stations 10505, 

 10506, 20056, 20058, 20059, and 20061), none at all in April, one in May (station 

 10277), none for June, July, or August, and one each for September (station 10317) 

 and October (station 10328). 



Thus Ditylium is chiefly an autumn and early winter form in the coastal zone 

 of the gulf, spreading offshore during the later winter and early spring. Fish (1925) 

 likewise found it a winter diatom at Woods Hole. 



Eucampla 



Eucampia zodiacus, like Guinardia, has been strictly confined to Georges Bank 

 in our towings, and to the coastal waters farther west and south, though Fritz (1921) 

 found occasional specimens at St. Andrews in one July tow. It shared with Guin- 

 ardia in the rich diatom flora that occupied the waters over the western part of the 

 bank on July 9, 1913 (station 10059, fig. 123); was sparsely represented in that same 

 general region in July, 1916 (station 10348), and again on February 22, 1920 (stations 

 20046 and 20047). The Arctic species, Eucampia gramlandica, has not been iden- 

 tified from the Gulf of Maine, but specimens apparently intermediate between 

 it and E. zodiacus (cf. Gran, 1908, p. 99, fig. 126b) occurred in some numbers 

 among the Guianardia-Eucampia community just mentioned (station 10059). 



Guinardia 



G.flaccida, the unique member of this genus, has only once been detected within 

 the Gulf of Maine (occasional specimens near Cape Ann, October IS, 1915, station 

 10330), and has not been reported at St. Andrews, but, as I have already noted 

 (p. 391), it swarmed locally on the western part of Georges Bank in July, 1913 

 (station 10059); again on the northeast edge in the same month in 1914 (station 

 10224). 



Guinardia is a summer, not a spring or autumn, diatom there, for it was only 

 sparsely represented on our line across the western end of the bank on February 

 22 and 23, 1920 (stations 20044 to 20046), and not at all on the more easterly sec- 

 tions for the two months following, or in the collection which Mr. Douthart gathered 

 on the bank during April, 1913. It is irregular in its occurrence on Georges Bank 

 even in July, for in that month in 1914 it was wanting in the region where it swarmed 

 in 1913, though abundant a few miles farther east at the time. It is a question 

 whether Guinardia appears there in such numbers every summer, for it was not 

 detected at all at our July stations on the western end of the bank in 1916 (stations 

 10347 and 10348), though the water was then full of other diatoms (Thalassiothrix 

 longissima and Rhizosolenia styliformis) . No towings have been made on the bank 

 during autumn, but Guinardia probably occurs there at that season as well as in 

 summer, the Grampus having found it flowering along shore west of Newport, R. I., 

 as late as November in 1916 (stations 10405 and 10406). Fish (1925) found it 

 regularly in winter at Woods Hole and only occasionally in summer. 



It is not surprising that Guinardia should be at its maximum on Georges Bank 

 during the July to September quarter, which is its flowering season in north European 



