86 University of California Publications in Zoology [Vol.22 



EOTIFERA 



Plates 3-6 and 15-17. 



Station I Station II Station III Daily Hourly 



Number of forms recorded.. 55 43 39 30 34 



Individuals per eu. meter.. 4,842,320 883,510 1,302,609 5,443,643 5,681.372 



Eggs 31% Eggs 45% Eggs 34% Eggs 29% Eggs 34% 



These averages are made from records which include males, fe- 

 males, eggs attached, a few records of free eggs, winter eggs, male 

 eggs and parasitized individuals. Further distinctions were not ad- 

 visable because of inability to carry them through the count with 

 accuracy. 



Rotifera were found in every collection through the whole year at 

 all stations. Only twice in the whole year did the numbers fall 

 below 75,000 per cubic meter at Stations II and III, and at no time 

 was a smaller number than 200,000 recorded at Station I. This makes 

 a remarkably consistent showing, especially by way of contrast with 

 Illinois conditions as found by Kofoid (1908). This consistency is 

 even more striking than are the distinctly larger numbers found here 

 at all stations. Both features are evidently due to the peculiar cli- 

 matic conditions of this region. There is agreement with Illinois 

 records in the fact that minimum production occurred in winter and 

 the maximum in warmer weather, though much later there than at 

 Station I. There is a difference in that the fluctuations were less 

 extreme here, and that maxima occurred in November at Stations II 

 and III. 



Recurrent pulses were fairly well marked at all stations though 

 the intervals were quite variable. These pulses were not coincident 

 with those of any other group. The maximum number of Rotifera 

 did not correspond in time with the maximum mass production of 

 plankton at any station nor did it agree with any other group. 



This group affords another illustration of a case in which a single 

 genus exerts a remarkable influence on the whole group, the late 

 maximum in November at Stations II and III being due to Keratolla. 

 Since, however, this same genus is largely responsible for throwing 

 the Illinois maximum into May, perhaps those records and ours can 

 be compared with some fairness. 



Catches of 1,000,000 or near that number were rare at tempera- 

 tures below 15° C. About eighty-seven forms of Rotifera were listed. 



The names used have been checked as closely as possible to cor- 

 respond with those indicated in Harring's Synopsis of the Rotatoria. 



