646 MR. R. GURNEY ON FRESH- AND BRACKISH-WATER CRUSTACEA. 
Cyclops languidoides, Lilljeborg. Sutton only, in the same 
places as C. languidus. This species, which has 
only recently been described, does not seem to differ 
in any respect from the preceding one except in its 
antennae, which are eleven-jointed. It should probably 
be regarded as a variety of C. languidus. 
„ vernalis, Fischer. 
„ bisetosus, Rehberg. Has been found by myself at 
Sutton, and by Mr. Scourfield at Catfield Fen. 
„ viridis, Jurine. 
,, diaphanus, Fischer. Taken by Mr. Scourfield in a pond 
on Mousehold heath (1903, p. 535). 
,, varicans, Sars. Sutton, Barton, Calthorpe, Catfield Fen, 
and in the Ant. 
,, rubellus, Lilljeborg. In Great Britain this species has 
only been recorded from the Lake District. In 
Norfolk it occurs in Sutton, Rollesby and South 
Walsham Broads. 
,, bicolor, Sars. 
„ fuscus, Jurine. 
„ alb i dus, Jurine. 
,, distinctus, Richard, = C. bistriatus, Koch. (Scourfield, 
1903, p. 535). It has been suggested that this form 
is a hybrid between the two preceding species, and 
certainly such a view is very plausible. On the 
other hand, the facts that it occurs so frequently 
in Norfolk, at all events, that it sometimes occurs 
without either of the “parent" species; and that 
it is occasionally found in considerable numbers, are 
at least evidence that it should be regarded as 
distinct. I have not been able to rear the larvae 
of it to the adult stage, nor have I succeeded in 
crossing the “ parent ” species. 
,, serrulatus, Fischer. I have not attempted to record 
separately the varieties of this species. Lilljeborg’s 
two species C. macmroides and C. varius both 
occur, but I believe they should be regarded as 
varieties, connected with C. serrulatus by inter- 
mediate gradations. 
