On Aquatic Carnivorous Coleoptera or Dytiscid(B. 551 



and moi-e distinctly sinuate beneath ; on the liind 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 oeneous tint on 

 its upper surface. 



Europe, (North America f), Sweden; Fiiiland to 63° 40', Sahlberg ; Britain, France, Germany, 

 Lithuania). 837. 



782. Dytiscus obscurus. Marsh., llyhius ohscurus, 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. \\h, 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 sliglitly more slender and 

 more distinctly bi-emarginate, so that it has in the middle an excessively minute 

 sharp proj ection ; 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, bub 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, is 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, baud elongatus, subtus 

 piceus vel rufus, supra seneus, limbo anterius plus minusve ferrugineo, antennis 



