508 On Aquatic Carnivorous Coleoptera or Dytiscide. 
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 seriesof strie forming a file(no doubt a stridulating organ) on each sideof the third 
ventral seyment ; prosternal process rather narrow, very little compressed, nearly 
glabrous or feebly punctulate ; anterior border of hind coxee 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 cilic at this spot very rudimentary. 
Four species from both Old and New Worlds. 
697. Agabus (Gaurodytes), biguttulus, Th. Sk. Col. TX, p. 110.—Oblongo-ovalis, 
niger, nitidus, supra sabsenescens, antennis pedibusque rufis, femoribus picescentibus; 
supra vel subtilius sed haud inconspicue (4) vel ubique evidenter (£) reticulatus : 
elytris punctis subseriatis haud profundis. Long. 6%, lat. 34 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 Agabus eeneolus, 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. eneolus (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.—Oblengo-ovalis, niger, vix 
supra subeenescens, antennis pedibusque rufis, femoribus picescentibus; subleevigatus, 
elytris guttula pone medium maculaque apicali pallidis. Long. 64, lat. 33 m.m. 
