On Aquatic Carnivorous Coleoptera or Dytiscidce. 531 



legs very approximate, so that the metasternal groove is excessively narrow and 

 indistinct. 



North America, (Oregou, Vancouvei-'s Island). 790. 



Group 20. 

 Coxal harder very wide ; the coxal lines gently, not abruptly, turned outwards at 

 the extremity ; prosternal process punctulate, slightly raised along the middle. 

 Four species from both Old and New Worlds. 



748. Agabus melanarius, Aube, Spec. p. .353, Agahus tarsatus, J/. C — Oblongo- 

 ovalis, niger, sat nitidus, supra hand perspicue genescens, antennis rutis, pedibus 

 piceis ; fortiter conspicue reticulatus, prothorace lateribus vix rotuudatis, angulis 

 posterioribus obtuse rectis ; prosterni processu punctulato medio glabro. Long. 9, 

 lat. 5 m.m. 



The male has the three basal joints of the front and middle tarsi a little 

 thickened, and furnished beneath with very short glandular hairs : the anterior 

 claw of the front foot is slightly thickened, and its lower margin a little sinuate. 



Northern Europe. (Sweden, Finland, Denmark, Germany, Russia). 730. 



749. Agabus tristis, Aube, M.C. — Oblongo-ovalis, superne minus convexus, sat 

 Tiitidus, fusco-niger, prothoracis lateribus, et vitta transversa post marginem anterio- 

 rem, elytrisquehumeris plus minusve discrete rufescenti bus, antennis pedibusque rufis, 

 posterioribus plus minusve infuscatis, corpore subtus plus minusve rufo-variegato ; 

 .supra undique evidenter reticulatus reticulis magnis. Long. lOi, lat. 5j m.m. 



The male has the three basal joints of the front and middle tarsi much incrassate 

 and amply furnished beneath with short glandular hairs : the claws of the front 

 feet are moderately long, and are scarcely at all more developed than in the female, 

 but the anterior one has a tooth at its extreme base : there is a .slight difference 

 in the sculpture of the sexes, the female having the scratches on the basal portion 

 of the elytra placed in a rather more regular and oblique direction, and the meshes 

 formed by them are more elongate. 



The species varies a good deal in colour. 



Eussian America: Arctic Sibei-ia, (Diidinka, Sahlberg). 791. 



750. Agabus woUastoni, u. ^). — Mas et femina perdissimiles ; oblongo-ovalis, 

 minus convexus, subtus niger, antennis palpis pedibusque rufis ; supra undique 

 subtiliter sed evidenter reticulatus ; prothorace basi elytrorum latitudine, lateribus 

 obliquis, minus rotundatis, anguUs posterioribus vix obtusis. Long. 11, lat. 6 m.m. 



TRANS, ROY. DIB. SOC, N.S.. VOL. II. ^ ^ 



