110 University of California Publications in Zoology [Vol.22 



found in abundance in some of the shallow temporary ponds in Stock- 

 ton in February, March and April, hence it is to be regarded as 

 adventitious in the plankton collections. 



Cyclops sp. 



Station I Station II Station III Daily Hourly 



Average 165,660 2,23S 7,929 525,978 83,099 



Identification of genus usually certain. May include some other 

 genera when preservation of the individual was poor. As mentioned 

 above, Dr. Marsh has indicated the presence of three species in the 

 first half year. These were C. americanus Marsh, C. prasinus Fischer, 

 and C. albidus Jurine. It is probable that there were few other 

 species and that these furnished the principal numbers. 



The genus was rarely missing at Station I, though the numbers 

 were comparatively small before May and in December. Only two 

 catches were recorded before June 21 at Station II and two after Sep- 

 tember 13. Conditions were somewhat the same at Station III, 

 though the number of catches before mid-June was larger. The evi- 

 dence seems to be conclusive that the genus is favored by sewage, by 

 stagnation and by high temperature. It does not seem possible that 

 recounting by any method could change the basis for such conclusions. 



There is some evidence of recurrent pulses at Station I but a 

 recount would be necessary before listing them with full confidence. 

 As it stands, no very close relationship to the algal pulses can be 

 shown except in two or three cases. 



Diaptomus sp. 



While this genus does not appear in the record, it is so certain 

 that it was present that definite mention of the fact seems desirable. 

 It may have been sometimes included in the count with Cyclops, but 

 the numbers were never very large and it may have failed to get into 

 the counting field except in one or two cases. 



NaupUus spp. 



Station I Station II Station III Daily Hourly 



Average 392,240 11,722 5,239 962,366 106,370 



All kinds of larval copepods were included under this heading. 

 Undoubtedly, nearly all belonged to Cyclops. They showed practically 

 the same characteristics of distribution at all stations as those already 

 noted for Cyclops, almost the only difference being that more catches 

 were recorded. This might be expected since such a variety of larval 

 forms was included in the count. 



