442 University of California Publications in Zoology [Vol. 22 



the fact that Chactoccras debile CI. and Nitzschia seriata CI. showed 

 similar differences on a smaller scale. 



Surface catches taken on a run thirty miles northward late in 

 June gave no certain indication of anything except that catches of 

 diatoms differ greatly in numbers at different points. There is not 

 the slightest indication of uniform distribution over a wide area, 

 although one may properly suppose that conditions may sometimes 

 arise, just as they do on land, whereby some one plant is enabled to 

 reach a very heavy production and therefore an apparent uniformity 

 over a wide stretch of territory. 



DINOFLAGELLATES 



Although in most catches dinoflagellates were not numerous in 

 either May-June or September, a total of thirty-seven species was 

 recorded. Of these only seven reached sufficient prominence to be 

 listed with the first five in average production at any level. Of the 

 seven Cera.tium tripos (0. F. M.) was the only one prominent in 

 May-June at all levels at both stations. In September it was among 

 the first five only at the surface at Station II. In no case was the 

 identification positive, the lateral horns usually being broken off close 

 to the body. Prorocentrum micans Ehr. was among the first five at 

 twenty and forty meters at Station I and at the surface at Station II 

 in May-June and at all levels at both stations in September. Dino- 

 physis homunculus Stein was among the first five at all levels at both 

 stations in September. The other species represented in the first five 

 at some place in the two periods were Peridinium dwergens Ehr., 

 Peridinium ovatum (Pouch), Peridinium sti ■inii Jorg., and Ceratium 

 furca (Ehr.). No catch of dinoflagellates was so great as 30,000 to 

 the liter, but this poor showing is probably due to the fact that both 

 series of catches were taken at the wrong season for large numbers. 



PHYSICAL AND CHEMICAL CONDITIONS 



Although light is recognized as a prime factor in determining the 

 quantity and distribution of diatoms (without considering other 

 organisms), we have not yet developed a satisfactory method of 

 identifying its influence in this area. Recent experiments in the 

 Puget Sound region ( Shelf ord and Gail, 1922), which show optimum 



