470 Miss Edith M. Pratt on the 



Copepods were most abundant some little distance below the 

 surface, while the Daphnids were found in greatest numbers 

 at the surface. The following forms were taken : — Copepoda : 

 Cyclops Kaufmanni was very abundant ; Cyclops signatus 

 and Diaptomus gracilis were abundant ; Cyclops insignis, 

 C. Ewartiy C. str enuus, a.nd DiaptoiHiis castor were less abun- 

 dant; Cyclops Thomasi was Ya.ye. Cladocera — Daphnid^ : 

 Bosmina longirostris and Sida crystallina were abundant ; 

 Chydorus sphcericus and the larvae only of Leptodora hyalina 

 were less abundant ; Bytliotrephes longimanus, Polyphemus 

 pediculuSy and Daphnia pulex were rare. 



On loth, 16th, and 17th June, 1898, sixteen tow-nettings 

 were taken at different hours of the day at depths from to 

 about 10 feet from tlie surface. 



This collection was characterized by the presence of the 

 rotifer " Asjjlanchna pri'odonfa^^ in immense numbers. As 

 it occurred in the same proportion in all the tow-nettings, it 

 must have been universally distributed. 



In April the Copepods outnumbered the Daphnids, but in 

 June the Copepods had diminished remarkably in numbers 

 and were replaced by those Daphnids (Dythotrephes, Poly- 

 phemuSj Leptodora^ and Daphnella) which were rare in April. 



The following Copepoda were taken: — Cyclops signatus 

 was fairly abundant ; C. phaleratus, C. strenuus, C. serru- 

 latus were rather rare ; C. insignis was rare. 



Daphnids : Dap>hnella brachyura^ Leptodora hyalina^ 

 Polyphemus pediculus were very abundant, with eggs, 

 embryos, and young in various stages of development ; 

 Bythotrephes longimanus with eggs and embryos was abun- 

 dant ; Sida crystallina and Chydorus sphcericus were rare. 



A few water-mites were taken which have not yet been 

 identified. 



The following species were abundant in April 1898, but 

 were rare or not taken in June : — Cyclops Kaxifmanni^ C. in- 

 signis, C. Ewarti, Diaptomus gracilis^ D. castor , Bosmina 

 longirostrisj Sida crystallina, Chydorus sphcericus. 



Cyclops Thomasi and Daph?iia\\eve rare in April and were 

 not taken in June. 



The following species were common in June which were 

 rare or not taken in April : — Daphnella hrachyura (absent in 

 April), Leptodora hyalina (only larvffi were taken in April), 

 Polyphemus p)ediculus, Cyclops phaleratus, and G. serrulatus 

 (fairly abundant, but not taken in April), Bythotrephes longi- 

 manus. 



Cyclo])s signatus and C. strenuus were fairly abundant in 

 April and in June. 



