SURFACE CATCHES OF MARINE DIATOMS AND 
DINOFLAGELLATES WADE BY U..S.S. 
PIONEER BETWEEN SAN DIEGO 
AND SEATTLE IN 1923 
BY 
WINFRED EMORY ALLEN 
(Contribution from Scripps Institution for Biological Research of the University of California) * 
In the latter part of February, 1923, the United States Coast 
and Geodetic Survey Steamer Pioneer ended her winter work in the 
San Diego region and turned northward to prepare for summer work 
in Alaskan waters. On the northward trip, hourly collections were 
taken in the same way that they had been taken in the San Diego 
region (Allen, 1923). This series of collections was continuous to 
San Francisco. Collecting was resumed the first week in' April and 
was again continuous as far as Seattle. It comprises a total of 119 
catches from fifteen miles north of San Diego to a point near Seattle 
in Puget Sound. 
On account of the uniform frequency of sampling in this series, 
it has seemed desirable to make somewhat different designations of 
regional units from those formerly used (Allen, 1922). Although 
arbitrarily selected, the limits of these re'gions have been largely 
determined by the more prominent coastal topographic features. (See 
map, fig. 1.) The position of the last catch in each region has been 
taken as the distal boundary of that region. 
In seven out of -the^ eleven regions designated, at least a few 
diatoms were recorded for every catch. Of dinoflagellates, this was 
true in only two regions. In five regions, the largest catch of diatoms, 
and in four regions the average number of diatoms to the catch, were 
greater than 50,000 to the liter. In only two regions did catches of 
dinoflagellates reach 1000 to the liter, and in no region was the 
average to the catch so great as 1000 to the liter. (See table 1.) 
Fifty-one species of diatoms, representing twenty-two genera, were 
recorded between San Diego and Seattle. The more important of 
* Published by permission of Col. E. Lester Jones, Director of the TJ. S. Coast 
and Geodetic Survey. 
