MR. R. GURNEY ON FRESH- AND BRACKISH- WATER CRUSTACEA. 649 
Eurytemora lacinulata, Fischer. This species is generally 
regarded as a brackish-water form, but in Norfolk it 
is found in nearly all the Broads, and, in brackish 
water, is almost entirely replaced by E. atfinu. 
,, affinis, Foppe. An estuarine, or even marine, species 
found most abundantly in the lower reaches of the 
rivers of Norfolk, but extending far up them even 
into fresh water. I have even taken it once at 
Sutton and twice at Barton. Roughly speaking, 
I have found these two species mutually exclusive. 
Argulidas. 
Argulus foliaceus (Linn.). I have not specially searched for 
the parasitic Copepods, so that I have only recorded 
this species when taken swimming free. It seems to 
be generally distributed. Probably it will be found 
that such species as Arh/heres •percarum , Nordm., 
occur upon some of our fresh-water fish, and I should 
be very grateful if those who have the opportunity 
would send me specimens of any fish parasites which 
they may come across. 
Macrura. 
Palaimonktks varians (Leach). This species is a common in- 
habitant of estuaries and brackish ditches, though 
it can accustom itself to almost entirely fresh water, 
and in South Europe is only found in the latter. 
In Norfolk I have found it in Oulton Broad, the 
Muckfleet, in the Yare at Seven-mile House, and 
in brackish ponds and ditches at Cley. In one of 
these ditches at Cley it was associated with a typically 
fresh-water fauna, and I imagine the salinity of the 
water must have been exceedingly low. 
Schizopoda. 
Neomysis vulgaris (J. V. Thompson). The distribution of this 
species is very interesting. It occurs commonly in 
the rivers Yare, Bure, and Waveney within the 
strictly estuarine region, and may be found in 
thousands along their banks. But though it is not 
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VOL. VII. 
