640 MR. R. GURNEY ON FRESH- AND BRACKISH-WATER CRUSTACEA. 
As regards the nomenclature used ; I have followed, for the 
Cladocera, Lilljeborg’s “ Cladocera Sueciae.” For the Copepoda 
I have used the nomenclature of Schmeil (Deutschlands freilebende 
Siisswasser-Copepoden) with certain alterations made necessary by 
the papers of Lilljeborg (1901 and 1902) and Scott (1903). 
CLADOCERA 
SlDID/E. 
Sida crystal lina (0. F. Muller). Occurring commonly in all 
the fresh-water Broads with one or two exceptions, 
blot in the Hickling region. 
Diafhanosoma brachyurUm (Lievin). Distribution much as fo 
the preceding species. 
Daphnid e. 
Daphnia magna, Straus. Common throughout the district in 
farm ponds, but rather capricious in its occurrence. 
Apparently in other parts of England it is rare. 
, Atkinsoni, Baird. This species has hitherto been found 
only near Staithes in Yorkshire. On June 16th of 
last year, Mr. R. A. Todd found it abundant in 
ponds near Happisburgh, and I have myself found 
it since then both in the same ponds, and in ponds 
at Honing and Brumstead. 
,, pulex (De Geer). I have not separately recorded the 
different varieties of this species, but D. hamata, 
Brady, and 1). obtusa, Kurz certainly occur frequently. 
The latter is the most distinct of these varieties, but 
I have found males agreeing in all respects with 
those of D. obtusa associated with females of the 
typical D. pulex. 
„ longispina, O. F. Muller. Abundant in clear water 
all over the district, but only exceptionally found in 
large open waters, where its place is taken by the 
pelagic species D. cucullata and D. lacustris. In 
fact, it seems likely that the latter is only a strongly 
marked variety of D. longispina adapted to a pelagic 
existence. 
