300 MR. F. BALFOUR BROWNE ON AQUATIC COLEOPTERA. 
visit, there had been enough water to make a collection which 
was rich in species and individuals. I re-visited the same 
ditch g days later after there had been some rain and made 
a collection there. I found 13 species of Hydradepliaga, and 
5 species of Palpicornia, and the two dominant species were 
Ilybius ater, De G. and obscurus, Marsh. I counted 14 
specimens of the former and 17 of the latter, and there were 
more individuals of both species. All the 14 Ilybius ater 
and 16 out of the 17 I. obscurus were soft specimens quite 
recently emerged from the pupal condition. During the 
same month I found, in two adjacent ponds in the Palling 
Brick Pits, crowded centres of Ilybius fuliginosus, F., the 
majority of specimens in both cases being soft, some even 
being brownish, and not yet fully pigmented. 
I noticed, however, fewer crowded centres in the autumn 
last season, than in 1904, and my records for soft specimens 
mostly refer to one or a few individuals only. All immature 
specimens observed occurred in June (July, 1904), August, 
and September with the exception of one record in the latter 
part of May. In the subjoined table I have included all 
the cases observed : — 
May. 
June. 
[July, 1904.] 
August. 
September. 
Agabus 
Hydroporus 
Hydroporus 
Pelobius tardus, 
Noterus 
bipustulatus, L. 
gyllenhalii, 
gyllenhalii, 
Herbst. 
clavicornis, 
Common in one 
Schiodte 
Schiodte. 
Hydroporus 
DeG. 
or two dykes. 
1 Iydroporus 
Anacsena 
incognitus, 
(one sp. only). ( 
pubescens, 
globulus, Payk. 
Sharp. 
Agabus 
Gyll. 
Anactena 
Copelatus 
bipustulatus, L. 
Agabus 
bipustulatus, L 
Agabus 
nebulosus, 
Forst. 
Agabus 
chalconotus, 
Panz. 
Ilybius 
fuliginosus, F. 
Ilybius 
ater, De G. 
Ilybius obscurus, 
Marsh. 
limbata, F. 
agilis, F. 
Rhantus grapii, 
Gyll. 
Rhantus 
exoletus. Forst. 
Agabus 
nebulosus, 
Forst. ' 
Rhantus 
exoletus, Forst 
Dytiscus 
marginalis, L.1 
Hydrophilus 
piceus, L. 
Helochares 
punctatus, 
Sharp. 8 

