448 University of California Publications in Zoology [Vol. 22 



The exceptional catch of more than 200,000 to the liter at a 

 point about seventeen miles southeast of San Clemente Island seems 

 somewhat abnormal in comparison with all the others of the series. 

 Chaetoceras seolopendra CI. made up more than half of this catch, 

 and, with other small species of Chaetoceras, comprised almost the 

 whole number, although Bacteriastrum varians Lauder numbered over 

 ten thousand. Evidently this is a good example of localized swarms 

 of minute organisms which we know to occur in open waters. 



Except for the large catch in section three, nearly all the larger 

 catches were made in sections one and two, and less than forty miles 

 from shore. In a general way this fact supports the common suppo- 

 sition that production of plants, even in open water, is greater near 

 the coast. 



Most of the catches were made at intervals of one hour. Since 

 they differ markedly in numbers, it is evident that distribution 

 throughout the area was not uniform even in those cases where hydro- 

 graphic data suggested the possibility of approximating to uniform 

 environmental conditions. 



Dinoflagellates. — The catches were also examined for dinoflagel- 

 lates but in no cases were their numbers great enough to have any 

 statistical value. All that can be said is that some were present. 



It was very fortunate that the U. S. S. Pioneer made two round 

 trips over the same ground in quick succession for it showed excep- 

 tionally well that within a very few days production may radically 

 change over a wide area in the winter season. This showing has 

 additional value because of the fact that it ran approximately parallel 

 with a similar change at the pier and makes it more than ever prob- 

 able that seasonal changes in production at the pier give a fair basis 

 for judging the general character of seasonal changes in this oceanic 

 area. 



Transmitted June 11, 192S. 



