1923] Allen: Studies on Marine Diatoms and Dino flagellates 437 



Consequently they will receive separate treatment hereafter, the 

 diatoms being given primary consideration because of their numerical 

 superiority and more typical synthetic activities. 



In September the average number of dinoflagellates to the catch 

 was considerably larger than in May-June excepting for the twenty 

 meter level at Station I. On the average, dinoflagellates outnumbered 



STATION 1 . 

 iAay ~ Juuq 1922 

 Graph f-o short /cgarS/hms o/" numbers' per 

 //'/■or o/~ diatoms- in /Co/bid bucket- catches'. 



Sur/sce cs/cAes 



20 meter cs/ctes ............ 



&0 me/-er catches oooooooooooooo 



^V 



HI III llll II I III llllllll 11 Mil I II llllllllllllllllll , llll 



Fig. 1 



the diatoms in September also except for the forty meter level at 

 Station II. Both groups were represented by smaller numbers in the 

 latter part of September than at the middle of the month. 



In the matter of productivity at different levels the general show- 

 ing is considerably different from that of 1921. In May-June, 1922, 

 diatoms were distinctly more numerous at the twenty meter level, 

 whereas in 1921 diatoms were found in largest numbers at the surface. 

 Dinoflagellates were found most numerous at the surface and least 



