1920] Allen: Plankton of the San Joaquin River 93 



identified when attached but the confusion was great when unat- 

 tached. Probably eggs of other genera were often included amongst 

 the free eggs. Eggs of species were not recorded. 



Only seven species and one variety were recorded, although there 

 were probably many more. The reference of many individuals to 

 some of these species was somewhat arbitrary, but on the whole the 

 eight groups were fairly definite in the writer's mind and may be 

 properly discussed despite some technical error in identifying. 



Since the eggs were only recorded for the genus as a whole their 

 averages and the main features of their occurrence may be stated 

 now. 



Text Table 4 



Station I Station II Station III Daily Hourly 



Av. female eggs attached 2.55,960 1(5,390 28,607 409,180 1.32,240 



Av. male eggs attached.... 26,190 2,77.3 4,443 4,238 22,806 



Av. female eggs free 351,039 14,780 41,963 718,362 396,720 



Av. male eggs free 817 157 



In view of the uncertainty of identification of unattached Brach- 

 ionus eggs either male or female, it is hardly worth while to attempt 

 any detailed discussion of the records for these kinds. The maximum 

 for both kinds of attached eggs came early in March at Station I. 

 Occurrence of attached male eggs was scattered after Marcli, though 

 the female eggs were almost constantly present through the year. 

 They almost reached the March maximum twice in September. At 

 Station II there were only three records of male eggs, two coming in 

 March. Occurrence of female eggs was fairly constant from June to 

 October inclusive, infrequent at other times, the maximum coming 

 in October. At Station III male eggs were recorded seven times, the 

 maximum in March. The female eggs occurred rather regularly from 

 February to October inclusive, excepting April, when there were 

 none. The maximum came on October 4. About the only safe con- 

 clusion to be drawn from these inadequate records is that male eggs 

 are most numerous in early springtime at all stations. It is, of course, 

 unfortunate that the attached eggs were not segregated with the 

 proper species, but the desirability of segregation was not realized 

 until too late in the count. 



Brachioiius aiigularis Go.sse. 



station I station II Station III Daily Hourly 



Average 78,367 3,417 4,675 14,579 8,630 



Identification usually satisfactory. Occurrence far most conspicu- 

 ous in May and June at Station I, with maximum in mid-May. Miss- 



