On Aquatic Carnivorous Coleoptera or Dytiscide. 551 
and more distinctly sinuate beneath ; on the hind foot of this sex the outer claw is 
shorter than the inner one, and has a more acuminate curved-down termination ; 
the apical ventral segment has an elevated carina along the middle on the hinder 
part, and is longitudinally plicate-rugose on each side. In the female the outer claw 
on the hind foot is greatly curved, and the apical ventral segment at the extremity 
is compressed in the middle, so that its extremity appears to bear a notch. 
The species is subject to a little variation in colour, being sometimes more 
piceous than black, and having the sides of the thorax and basal portion of the 
elytra more dilute in colour. It has only a very slight trace of an neous tint on 
its upper surface. 
Europe, (North America’), Sweden; Finland to 63° 40’, Sahlberg; Britain, France, Germany, 
Lithuania). 837. 
782. Dytiscus obscurus, Marsh., Ilybius obscurus, M.C.—Ovalis, convexus, niger, 
subtus piceus, antennis pedibusque quatuor anterioribus rufis, pedibus posterioribus 
piceis, supra sub-opacus densius reticulatus, reticulis ad elytrorum apicem obsoletis, 
elytris guttulis duabus pallidis ; coxis posterioribus evidenter reticulatis, margine 
anteriore externe parum curvato. Long. 113, lat. 6 m.m. 
The male has the three basal joints of the front and middle tarsi distinctly 
incrassate and much compressed, and clothed beneath with rather long hairs 
bearing minute palettes ; on the front feet the anterior claw is not thickened but 
is distinctly emarginate beneath, while the hinder one is slightly more slender and 
more distinctly bi-emarginate, so that it has in the middle an excessively minute 
sharp projection ; the posterior claw on the middle feet has a tendency to assume a 
similar form, but is sometimes quite simple; the outer claw of the hind tarsus is 
short, stout and quite obtuse at the apex; the apical ventral segment has a carina 
on the middle of its hinder part, but is but little rugose on each side; the female 
has the ventral segment plicate-emarginate at the extremity, but so as generally 
to appear less emarginate than in Dytiscus ater, the outer claw of its hind foot is 
acuminate and curved at the extremity. 
This species is smaller than Dytiscus ater, (No. 781), and has the reticulation of 
the elytra more obsolete at the apex, it has no seneous tinge ; the male can be very 
easily distinguished from that sex of D. ater by the much less development of the 
hairs of the tarsi. It is more variable in form than D. ater, some individuals 
being a good deal more elongate than others. Ilybius sexdentatus, Schiodte, 1s one 
of the varieties of this species. 
Europe ; (Sweden ; Finland to 68°, Sahlberg ; Britain, France, Germany). 832. 
783. Ilybius subeeneus, Er., M.C.—Ovalis, convexus, haud elongatus, subtus 
piceus vel rufus, supra seneus, limbo anterius plus minusve ferrugineo, antennis 
