624 On Aquatic Carnivorous Colcoptera or Djjtiscida. 



similar manner to the front feet, their claws are very unequal, the outer one being 

 very thick and moderately long, twice the length and twice the thickness of the 

 more arcuate inner one. In the female there is a distinctly reticulate area on the 

 elytra in front of the middle towards each outside. 



Madagascar. 905. 



959. Rhantus validus, n. sp. — Ovalis, sat convexus, elongatus, nee latus, nitidus, 

 fere L-evigatus, subtus nigricans, prosterno rufescente, supra testaceus, vertice nigro- 

 variegato, thorace disco plaga parum discreta fusca, elytris nigro-irroratis, antennis 

 pedibusque anterioribus rufi'^, pedibus posterioribus piceo-i'ufis : prothorace sine 

 margine laterali ; tarsis posterioribus extas vix lobatis. Long. ISi, lat. 8 m.m. 



The male has the front and middle tarsi a good deal incrassate and much com- 

 pressed, and furnished beneath with long hairs, bearing narrow palettes, and the 

 claws are moderately long, simple and equal. The female shows scarcely any 

 greater development of sculpture than the male. 



South America, (Cliili). 906. 



I. (; 3. —Genus COL YM BETES. 



Side pieces of fourth and following ventral segments very nari-ow ; metasternal 

 groove narrow and indistinct ; terminal joint of hind tarsus not longer than the 

 preceding one. Wing-cases marked wiih transverse scratches, or (more rarely) 

 smooth. 



The eighteen species'"' of this genus are found in the northern parts of the Old 

 and New Worlds; but one or two extend as far to the South-east as North- 

 western Arabia. 



9G0. Colymbetes dahuricus, Aube, Scutopterus dahiiricus, M.C. — Ovalis, in medio 

 dilatatus, convexus, niger, fintennarum basi testaceo, clypeo rufo, vertice rufo- 

 bimaculato, thorace elytrisque testaceis, his infuscatis margine pallidiori, illo in 

 medio nigricante; corpore strigoso, strigis in elytris transversis, hand profundis ; 

 elytrorum epipleuris in medio latioribus etmagis elevatis. Long. 19i, lat. 10 m.m. 



* The following species also no doubt belong to this geuus, viz. — Colymbetes drewseni, Lee. (No. 1224 

 huj. op.)? No. 967 var. ; Greenland. — Colymbetes insequalis, Horn, (No. 1232) near No. 963; North 

 America. — Colymbetes simplex, Walk, (No. 1248)? near No. 975 ; Arabia. — Colymbetes strigosus, Lee. 

 (No. 1251)?=No. 964; North America. — CjTuatoi.terus obscuratus, Mann. (No. 1284) near No. 961; 

 North America, — whether ColjTiibetes includens, Walk. (No. 1233; Arabia) belong to the genus or not 

 is doubtful. 



