MR. R. GURNEY ON FRESH- AND BRACKISH-WATER CRUSTACEA. 643 
Camptocercus Lilujeborgii, Schoedler. Only quite recently added 
to the British list, being taken by Mr. Scourfield in 
the Ant near Sutton Broad in 1898. It is fairly 
common in Catfield Fen, where C. redirostris does 
• not occur, and has been found several times at 
Sutton. 
Acroperus iiarp.k, Baird. Common almost everywhere, and 
exceedingly variable. 
,, angustatus, Sars. The first British specimens of 
this species were taken by Mr. Scourfield in the Ant, 
and he has since shown me one taken in Sutton 
Broad. In all the hundreds of specimens of Acro- 
perus which I have examined during the past year, 
I have seen none that were not referable to A. harpa, 
for I believe that all intermediate variations occur 
between the two species. Another point which 
seems to me to be of great importance is this : 
though, during < Ictober and November, ephippial 
females of A. liarptr are quite common, I have 
never seen a male at all answering to the descriptions 
given by Lilljeborg for that species. < )n the other 
hand, males exactly agreeing with that of A. angus- 
tatus are always to be found in company with the 
ephippial females of A. harjue. I believe, myself, 
that A. angustatus and A. harjxv arc extreme forms 
of one and the same species. 
Lynceus quadrangularis (0. F. Muller). This species, which 
very closely resembles L. ajHnis , is much more con- 
stantly confined to muddy bottoms than the latter. 
„ AFEiNis, Leydig. 
,, tenuicaudis (Sars). Very rare. Hickling, Sutton, 
Catfield Fen and ponds at Brumstead and 
Herringfleet. 
„ costatus (Sars). 
,, guttatus (Sars). 
,, rectangulus (Sars). Common, especially in soft yellow 
mud, rich in Marsh Gas. This mud, which is of 
a quite characteristic appearance, is the favourite 
haunt of several of the rarer bottom forms, such as 
Leijdigia and Ilyocryptus . 
