VV hen staying in the month of September 1892 at our littlc 

 freshwater biological station at Finspong, I observed one day 

 in the pond next the building large. elondy swarms of ento- 

 mostraca. These swarms were spread över a space. 2 — 3 me- 

 ters wide, where they seemed to have given a red colour to 

 tlie water just as is known to be the case especially with the 

 JJaphnia pulex. Though the species in qiiestion had not been 

 f(mnd in the pond by previous researohes. 1 caught on the 

 16**^ of September by means of a very tight Muller's tow-net 

 a great nnmber of specimens. and a few days låter J caught 

 sonie more at the same spöt, where they still swarmed, * 

 evidently in the process of propagation. A closer examina- 

 tion proved both males and females to be present, the for- 

 mer more scarce. and, besides. young ones in different stages 

 of exuviation. Considering the circumstances under which 

 they were found, it can not be doubted that all the collected 

 specimens belonged to one -and the same species. To judge 

 from the very few and scanty reports in the otherwise rather 

 extensive literature, the development of the young after leav- 

 ing the matrix seems to be a part of the biology of the 

 Cladocera somewhat neglected. It was then ver^^ interesting 

 to examine these young forms; but as official duties very 

 soon forced me to return to Stockholm, I had only time to 

 make a few sketches of living specimens at Finspong. How- 

 ever, a collection was preserved in alcohol for future in- 

 vestigations and brought to Stockholm. The pond was emptied 

 s(jon after I left the station, and was kept dry during the 

 unusually severe winter of last year 1893. When I returned 

 the following summer I could not find any Daphnids, although 



I could not tind them in any other part of the pond. 



