On Aquatic Carnivorous Coleoptera or Dytiscide. 553 
gineis ; supra subnitidus, crebrius vix subtiliter reticulatus, elytris guttulis duabus 
(quarum anteriore elongata et conspicua) testaceis ; coxis posterioribus subtiliter 
strigosulis, margine anteriore externe haud subito curvato. Long. 124, lat. 6; m.m. 
The species differs from Ilybius pleuriticus, by its more convex less parallel form 
and the different reticulation of the upper surface. I have one mutilated individual 
only of the male before me, its sexual characters seem to be quite the same as in I. 
pleuriticus, but its hind feet being quite gone I cannot speak positively on this 
point ; the female has the apical notch broader than it is in I. pleuriticus. The 
form of the species makes it very similar to I. subeeneus, but it is readily dis- 
tinguished therefrom by its more shining and coarser reticulated upper surface, and 
by the rather more slender outer portion of the metasternal wings. 
North America. 841. 
786. Ilybius quadrimaculatus, Aube, M.C.—Ovalis, sat elongatus, minus convexus, 
subtus niger, supra nigro-zeneus, antennis rufis, articulis 7-10 extrorsum infuscatis, 
pedibus piceis, elytris guttulis duabus testaceis, epipleuris nigro-zneis, supra sub- 
opacus, densius subtiliter reticulatus ; coxis posterioribus subtilius strigosulis et 
punctatis, margine anteriore externe haud abrupte curvato. Long. 114, lat. 6 m.m. 
The male has three basal joints of the front and middle tarsi, distinctly incrassate, 
and furnished beneath with moderately long hairs, which bear small palettes ; of 
the front claws the anterior one is slightly thickened, and nearly straight beneath, 
while the hinder one is a good deal emarginate near the base ; on the hind feet the 
outer claw is nearly similar in form to the inner one, except that it is a good deal 
shorter ; the last ventral segment, has a much elevated carina on the middle of its 
apical portion, and is also coarsely rugose ; the female has the last segment also 
carinate, and appearing to bear only a very small notch, and is without rugosities. 
The species is of a more black colour than its near allies. 
North America. 842. 
787. Ilybius crassus, Th., M.C.—Ovalis, haud elongatus, convexus, subtus nigri- 
cans, supra nigro-zeneus, antennis pedibusque anterioribus rufis, posterioribus piceis ; 
elytris subopacis, densius reticulatis, punctis subseriatis conspicuis ; coxis posteri- 
oribus subtiliter strigosulis, margine anteriore extus sat abrupte curvato. Long. 
113, lat, 64 m.m. 
The male has the basal joints of the front and middle tarsi a little incrassate, and 
furnished beneath with moderately long hairs bearing small palettes ; the claws on 
the front feet are moderately long, and nearly simple, the hinder one being how- 
ever distinctly emarginate near the base; the outer claw on the hind foot is thick- 
ened, and subobtuse at its apex, without any defiexed point; the male has no 
