94 U Diversity of California Publications in Zoology [Vol.22 



ing in January, February, and December, rare in March, April, July, 

 August and October. Occurrence at Station II from April to Novem- 

 ber inclusive, but scattered and in small numbers with a maximum 

 in September. Limited to same period at Station III but regularly 

 recorded during most of May and June with maximum in May, 

 favored by sewage and by a temperature near 20° C. Stagnation 

 seems to be detrimental. 



The periods of regular occurrence were too short to give very well 

 marked evidence of recurrent pulses. 



Brachionus angularis cauclatus B. and Da. 



Station I Station II Station III Daily Hourly 



Average 323,532 65,243 70,480 830,657 1,284,905 



Identification usually satisfactory. Sometimes hard to distinguish 

 from type form of B. angularis. The separate record of this variety 

 seems to have been worth while because of the tremendous emphasis 

 which it gives to the continuity in occurrence of the two forms. The 

 variety was almost wholly absent from the collections until the type 

 form had passed the spring maximum. As the latter declined the 

 former increased until it entirely displaced the other. This was strik- 

 ingly true at all three stations. The variety also disappeared by No- 

 vember at all stations, at which time the type came in in small num- 

 bers for a few weeks. At Station I the maximum came on June 25 

 but was almost equalled in September. At both of the other stations 

 the maxima came in August. 



Recurrent pulses were very marked in the records for this form 

 as shown by the following table : 



Text Table 5 



Station I Station II 



June 7 



June 25 



Julv 12 July 12 



July 26 



Aug. 20 Aug. 15 



Sept. 9 Sept. 20 



Sept. 27 



Oct. 11 



Comparison with the table of ploiman pulses at Station I shows 

 that four of the B. caudal us pulses correspond exactly while two oth- 

 ers are very close. It is thus evident that the relationship of occur- 

 rence of this organism to that of the chlorophyll bearers is about as 

 intimate as that of the whole ploiman group. 



