126 EDITH M. PRATT, B.SC. 



Cyclops Thomasi was rare. Cladocera — Daphmd^e : Bosmina 

 longirostris and Sida crystallina were abundant ; Chydorus sphoericus 

 and the larvae only of Leptodora hyalina were less abundant ; 

 Bythotrephes longimanus, Polyphem.us pediculus, and Daphnia puleoc 

 were rare. 



On 1 5th, 16th, and 17th June, 1898, sixteen tow-nettings were taken 

 at different hours of the day at depths from to about 10 feet from 

 the surface. 



This collection was characterized by the presence of the rotifer 

 " Asplanchna priodonta " 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 (Bythotrephes, Polyphemus, Leptodora, and Daphnella) 

 which were rare in April. 



The following Copepoda were taken : — Cyclops signatus was fairly 

 abundant ; C, phaleratus, C. strenuus, C. serrulatus were rather rare ; 

 C. insignis was rare. 



DAPHNiDiE : Daphnella 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 abundant ; Sida crystallina and Chydorus sphoericus 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 Kaufmanni, C, insignis, C. Eivarti, 

 Diaptomus gracilis, Bosmina longirostris, Sida crystallina, Chydorus 

 sphoericus. 



Cyclops Thomasi and Daphnia pulex were fairly common in April and 

 were not taken in June. 



The following species were common in June which were rare or not 

 taken in April : — Daphnella brachyura (absent in April), Leptodora hya- 

 lina (only larvse were taken in April), Polyphemus pediculus, Cyclops 

 phaleratus, and C. sermdatus (fairly abundant, but not taken in April), 

 Bythotrephes longimanus, 



Cyclops signatus and C. strenuus were fairly abundant in April and 

 in June. 



