508 On Aquatic Carnivoroxts Coleoptera or DijtiscidcB. 



claws of the front feet are short, and the anterior is dilated beneath by a tooth 

 occupying the greater part of its length but having a sharp extremity. 



The specimen of Agabus punctulatus extant in Dejean's collection is a rufescent 

 variety of this species. 



North America, (Pennsylvania, Newfoundland, sec. Crotch). 756. 



Group 8. 



Form narrow and parallel ; males with short anterior claws dentate beneath, and 

 with a series of stricB forming a Jile{no doubt a stridulating organ) on each sideofthe third 

 ventral segment ; prosternal process rather narrow, very little compressed, nearly 

 glabrous or feebly punctulate ; anterior border of hind coxse much arched, wings of 

 the metasternum moderately large ; hind tarsi rather feeble, but the femora have a 

 distinct lamina at the postero-external angle, the cilire at this spot very rudimentary. 



Four species from both Old and New Worlds. 



697. Agabus {Gaurodytes) , biguttulus, Th. 8k. Col. IX, p. 110. — Oblongo-ovalis, 

 niger, nitidus, supra subaiuescens, antennis pedibusque rufis, femoribus picescentibus; 

 supra vel subtilius sed baud inconspicue (c?) vel ubique evidenter (?) reticulatus : 

 elytris punctis subseriatis baud profundis. Long. 6t, lat. 3| m.m. 



This species is very similar at first sight to Dytiscus affinis (No. 698), but the 

 serial punctures of the elytra are not so deep. There is considerable difference in 

 the sculpture of the sexes ; in the male the reticulation of the elytra is not much 

 more distinct than in .4gabus aeneolus, while in the female this sculpture is much 

 more marked, the rather large meshes of the reticulation do not however cause the 

 surface to be dull in this sex ; the male has the basal joints of the front and middle 

 tarsi distinctly thickened and furnished beneath with short hairs which bear distinct 

 palettes ; the claws of the front feet are short, and the anterior one bears beneath 

 a sharp tooth near the base. The elytra have sometimes two pale spots like 

 A. aeneolus (No. 696), but sometimes these cannot be distinguished. 



Gaurodytes boreellus, Sahl. (Not. fenn. XI, p. 409) is I consider a variety of 

 this species. 



North Europe, (Sweden, and Finland to 68°, according to Sahlberg). 755. 



698. Dytiscus affinis, Payk., Agabus affinis, M.C. — Oblongo-ovaHs, niger, vix 

 supra subsenescens, antennis pedibusque rufis, femoribus picescentibus ; sublsevigatu.s, 

 elytris guttula pone medium maculaque apicali pallidis. Long. 6i, lat. 3i m.m. 



