332 Birge — The Crustacea of the Plankton. 



species 5-6 or at most 9 eggs and considers the small number 

 an adaptation to limnetic life. C. brevispinosus often carries 

 18 eggs in each sac without difficulty. He finds no eggs from 

 October to February, while I find egg bearing females at all sea- 

 sons. Marsh ('97, p. 205), gives the maximum for C. fluviatilis in 

 Green lake in the autumn and gives no spring maximum. I 

 think that the difference in our observations is a characteristic 

 of the species rather than of the lakes examined. 



Epischura lacustris Forbes. 



This species found only occasionally in my collections. It is so 

 large in the adult condition as to be readily distinguishable by 

 the unaided eye and was counted in this way along with Lepto- 

 dora. Young, if present, were doubtless counted as Diaptomus. 

 No observations were made on this species in 1894. In 1895 it 

 appeared on June 20th, two specimens being seen. It was not 

 seen again until July, in which month it was found in 6 out of 

 18 observations, the number not exceeding 2 individuals in any 

 one catch. In August they were seen 6 times out of 13 obser- 

 vations, the maximum being 4, and the total number being seen 

 during the month being 12. In September the number was 

 about the same, but in October the number was greater, aver- 

 aging 6 in each of the 5 cases where they were seen, with a 

 maximum of 9. In November they were present in every ob- 

 servation, 7 in number, up to the 20th, with an average of 6.5, 

 and a maximum of 19. The species thus showed a decided ten- 

 dency to a maximum in late autumn. In 1897 the species ap- 

 peared on May 17th and in the latter part of that month aver- 

 aged 4 in each catch. In the first half of June the average was 

 3, and maximum 7; in the last half the average was 4, and the 

 maximum 7. In July the average was 2, and the maximum 7. 

 Only a very few scattered individuals were seen in August, and 

 none were found later. 



It is evident that the records of the two years are not at all 

 similar, and that the numbers of the species which were found- 

 are too small for profitable discussion. 



