620 On Aquatic Carnivorous Coleoptera or Dytiscidce. 



middle tarsi are clothed beneath in a similar manner to the front feet, and their 

 claws are moderately long, the outer being a good deal thicker and longer 

 than the inner one. The females have a slight difference of sculpture from the 

 males, the reticulations of the elytra on the basal portion beccming a little coarser 

 in a stripe-like manner ; this sculpture is very distinct in the specimens from North 

 America and Lapland, but in individuals from Central Europe can often be scarcely 

 detected. 



Europe, Siberia, and North America. (Sweden; Lapland; Finland to 68° 30' Sahlberg; Britain; 

 Belgium ; Northern France ; Germany ; Hudson's Bay ; Massachusetts). 896. 



950. Colynibetes tostus, Lee, M.C. — Ovalis, elongatus, minus convexus, testaceus, 

 vertice late nigro, elytris nigro-irroratis ; tarsis posterioribus articulo quarto extus 

 vix lobato-producto. Long. lOi, lat 54 m.m. 



The male has the front tarsi much incrassate, and comparatively little compressed, 

 and furnished beneath with large palettes, the marginal hairs are largely developed 

 and have beautifully curved extremities ; the claws are elongate and slender, the 

 hinder being a little shorter than the front one ; the middle tarsi are clothed 

 beneath in a similar manner to the front feet, their claws are rather long and not 

 thickened, the inner distinctly shorter than the outer one. 



North America, (Missouri). 897. 



951. Dytiscus exoletus, Forst., Rhantus exoletus, M.C. — Ovalis, parum convexus, 

 testaceus, vertice nigro-variegato, elytris nigro-irroratis ; tarsis j^osterioribus articulo 

 quarto extus lobato-producto. Long. 10, lat. 5i m.m. 



The male has the front tarsi moderately incrassate and a good deal compressed, 

 and furnished beneath with moderately large palettes, the marginal hairs are not 

 highly developed, the claws are very long and slender, the hinder one a little 

 shorter than the other ; the middle tarsi are clothed beneath in a similar manner to 

 the front feet, and their claws are rather long and slender, the inner one being a 

 good deal shorter than the outer. There is no sexual difference in the sculpture of 

 the elytra ; the apical ventral segment is in each sex indistinctly strigose in the 

 longitudinal direction. 



Although the thorax in this species is generally immaculate, it has sometimes a 

 round dark spot on each side of the middle near the base, and these spots are con- 

 nected together by a fuscous basal mark. Dytiscus melanojjterus, Zett. (Faun. 

 Lapp. I, p. 211) is considered to be a colour variety of this species. 



Europe, (Sweden, Finland, Lapland, Britain, France, Belgium, Germany, Algeria), 898. 



