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University of California Publications in Zoology [Vol. 22 



were collected. Each sample consisted of organisms caught by filter- 

 ing five gallons of water (dipped from the surface of the sea) through 

 a small net of No. 25 silk bolting cloth. On the first round trip 

 catches were made on January 22 and 23, outbound, and on Febru- 

 ary 2, inbound ; on the second trip, outbound on February 5 and 6, 

 inbound on February 8 and 9. These collections were turned over 

 to the Seripps Institution for statistical study. For convenience in 

 discussion the catches are arbitrarily assigned to five sections of about 

 eighteen miles each. Beginning with Long. 117° 20' W, the sections 

 were numbered consecutively to Long. 118° 40' W, each section 

 including 20' of longitude. Table 1 shows fairly well the surface 

 distribution of the diatoms in these sections. 



TABLE 1 



Diatoms 



San Diego to Cortes Bank — January-February, 1923 

 II. S. S. Pioneer 



Section 



First Bound Trip 

 2 3 



3,888 



7,150 



2,904 



15,104 



2,772 264 



18,898 198 



242 3,740 



4,576 229,188 

 16,038 



484 

 132 



528 



418 

 462 



Total 29,046 



233,390 



1,144 



Average 7,261 8,505 58,347 3S1 



Average to the catch for second trip — 13,456 to the liter. 



704 

 5,456 



779 



