On Aquatic Carnivorous Coleoptera or Dytiscide. 395 
wing-cases. They may be arranged in three groups as follows ; (but the distinction 
between the groups is not very marked, many of the species of the third group 
approximating to the preceding ones by the labrum being more or less retracted, 
and the front of the head not very distinctly emarginate). 
Group. 1.—Labrum much concealed, head rounded in front, and with a more or 
less distinct raised margin: form usually very short, (the margin on 
the head is always fine, sometimes very indistinct and obsolete). 
Species 381 to 389. 
Grove. 2.—Head rounded in front, and with a thick, but little elevated margin ; 
labrum moderately concealed, approaching so nearly to the upper- 
surface of the head, that there is a slight interruption in the middle 
of the thickened margin. Form short or rather short. Species 390 
to 392. 
Group. 3.—Front of head without margin, and truncate-emarginate in the middle 
in front, labrum little concealed or quite conspicuous ; form oval, 
more or less elongate. Species 393 to 423. 
Group 1. 
881. Dytiscus inaequalis, Fab., Hydroporus inequalis, M.C.—Brevis, convexus, 
‘sat latus, nitidus, sine pubescentia, ferrugineus, prothorace basi apiceque N1gro, 
elytris nigris margine externo signaturisque ferrugincis ; capite thoraceque crebre 
subtiliter, elytris crebre fortiter punctatis ; pectore fortiter, abdomine sat fortiter 
punctatis. Long. 3, lat. 2 m.m. 
The markings on the elytra are variable, the sutural portion is always black and 
the external portion yellowish ; sometimes the black portion is broken by some 
yellow irregular marks. 
A variety nearly black in colour from Armenia is in the collection of Wehneke. 
Abundant in Northern and Middle Europe ; (Algeria, Wehncke). According to Crotch the species 
has algo been found in Illinois, North America. 170. 
382. Hydroporus punctatus, Say, M.C.—Brevis, convexus, latus, sine pubes- 
centia, ferrugineus, prothorace basi elytrisque obscurioribus, his margine externo 
dilutiore, capite thoraceque crebre punctatis; elytris crebre fortiter punctatis ; 
pectore fortiter, abdomine sat fortiter punctatis. Long. 3, lat. 2 m.m. 
Closely allied to Dytiscus ineequalis, (No. 381), but rather different in outline, 
being broader in the middle and so less parallel in form, with the punctuation of 
the elytra rather dense, and the upper surface without distinct contrasts of colour. 
United States of North America, (Middle and Western States), 176. 
TRANS. ROY. DUB. SOC., N.S., VOL. II. 3.15 
