MR. R. GURNEY ON FRESH- AND BRACKISH- WATER CRUSTACEA. 
G57 
earlier than usual, while the wintry weather of April may have 
retarded others. The period of sexual activity, also, may prove to 
have been influenced by the quite abnormal summer of the past 
year. It will be seen that the species increased rapidly in number 
from February onwards and reached their maximum in September, 
the number being maintained in October, but then suddenly 
decreasing. The maximum of sexual activity occurred in October. 
The table is necessarily open to error in one respect. It has not 
been possible to collect in the same places, or to take the same 
number of collections every month ; consequently there are gaps 
which might otherwise have been filled, and these gaps affect the 
number of species recorded. However, I believe the error from 
Ibis source is not very material. 
Literature Referred to in the Preceding Paper. 
Brady, G. S., and Robertson, D.— 
“ The Ostracoda and Foraminifera of tidal rivers." Annals and Magi 
Nat. Hist. ser. 4, v ol. vi., 1870. 
Harmer, S. F. — 
“On the occurrence of the Well-shrimp, Niphargus, near Norwich." 
Trans. Norf. and Norwich Nat. Soc. vol. vi. p. 480, 1899. 
Lilijeboko, W. ‘Cladocera Sueeiie,' Upsala, 1900 — 
“ Synopsis speciermn hue usque in Suecisc observatarum generis Cyclopis.” 
Kongl. Svenska Vet.-Akad. Handl. Bd. 35, 1901. 
“ Synopsis specierum hue usque in aquis dulcibus Suecife observatarum 
familial Harpacticidarum.” Kongl. Svenska Vet.-Akad. Handl. Bd. 30, 1902. 
Schmkil, O. — 
“ Teutscblands freilebende Siisswasser-Copepoden.” Bibliotheka Zoologica, 
1892-1S97. 
Scott, T. — 
“ The Invertebrate Fauna of the inland waters of Scotland.” Part vii. 
“ Fifteenth annual report Fishery Board for Scotland.” Part iii. p. 316, 
1897. 
“Some observations on British Freshwater Harpacticids.” Annals and 
Mag. Nat. Hist. ser. 7, vol. xi . 19D3. 
Scourfield, D. J. — 
“A preliminary account of the Entomostraca of North Wales.” Journ. 
Quek. Mic. Club ser. 2, vol. vi. p. 127, 1895. 
“ Synopsis of the known species of British Freshwater Entomostraca.” 
Part 1, Cladocera. Journ. Quek. Mic. Club ser. 2, vol. viii. p. 431, 1903. 
Part 2, Copepoda. Journ. Quek. Mic. Club ser. 2, vol. viii. p. 531, 1903. 
