A LIMNOLOGICAL RECONNAISSANCE 47 



since the supply of light upon which it is dependent for 

 carrying on photosynthesis is most favorable in this region. 



Only four forms of green and blue-green algae were found 

 in the material, namely, Anabaena, Gloiotrichia, Micro- 

 cystis, and Staurastrum. They were present in relatively 

 small numbers so that these forms constituted a relatively 

 small portion of the total net plankton. 



Four genera of diatoms were present with Stephanodiscus 

 as the most abundant; the maximum number of this form 

 was found in the 5 m.-lO m. stratum. 



Ceratium was the most abundant protozoan and it ap- 

 peared only in relatively small numbers. A few specimens 

 of Dinobryon and a heliozoan were found in the m.-5 m. 

 stratum, while Vorticella was noted in the 5 m.-lO m. 

 stratum. 



The catches contained only a small number of rotifers and 

 they were confined principally to the epilimnion. They were 

 uniformly distributed in this stratum. 



The copepods were relatively the most abundant forms 

 and, with the exception of Canthocamptus, they were fairly 

 uniform in their distribution from surface to bottom. As 

 a whole they furnished the greater part of the material 

 obtained in each catch. Diaptomtis was more abundant 

 than Cyclops and furnished the major portion of the cope- 

 pod material. Two species of Diaptomiis were present, 

 namely, D. clavipes and D. siciloides. 



Adults of D. clavipes constituted about 4% of the total 

 number of Diaptomi, but the immature individuals of this 

 species composed about two-thirds of the total. These im- 

 mature specimens contained a rather large supply of re- 

 serve food in the form of oil globules and these gave a j^el- 

 lowish tint to the whole plankton catch. 



Cyclops was most abundant in the upper 10 m. and below 

 25 m., with very few individuals between these two depths. 

 The copepod nauplii also showed a similar vertical distri- 

 bution; they were much more numerous above 10 m. and 

 below 25 m. than in the intermediate strata. 



The Cladocera were represented by specimens of Bosmina, 

 Diaphanosoma and three species of Daphnia. A few indi- 



