On Aquatic Carnivorous Coleoptera or Dytiscida. 509 
The three basal joints of the front and middle tarsi are very little incrassate, and 
are furnished beneath with short hairs, bearing very small and indistinct palettes, 
the claws of the front feet are not elongate, and the anterior one has near the base 
a sharp prominent tooth: the difference in sculpture of the two sexes is extremely 
slight. The pale marks on the elytra are sometimes not easily detected. 
Northern Europe, and Siberia; (Sweden; Finland to 68°, according te Sahlberg; Britain, Northern 
France ; Germany). 754. 
699. Agabus stridulator, n. sp.—Oblongo-ovalis, nitidus, niger, vix supra sub- 
zenescens, antennis pedibusque rufis, femoribus picescentibus ; supra levigatus, nullo 
modo reticulatus. Long. 6, lat. 3$ m.m. 
The basal joints of the front tarsi in the male are almost without incrassation, 
and their clothing beneath is but little developed: the front claws are short, and 
the anterior one bears beneath a sharp prominent tooth. ‘There seems to be no 
sexual difference in the sculpture of the upper surface ; but on the undersurface 
the file on each side of the third ventral segment of the male is very distinct. 
The species is extremely closely allied to Dytiscus affinis, but is rather less 
elongate, and its surface is destitute of the very rudimentary reticulation which 
on careful examination may be detected in that species: the anterior tarsi of the 
male have the basal joints less incrassate, the prosternal process 1s narrower; and 
the hind coxa are just slightly smaller, so that the wings of the metasternum are 
just appreciably less reduced. As in D. affinis a pale dash may sometimes be seen 
near the side of each elytron about the middle, and another near the apex. 
North America, (Hudson’s Bay, Canada). 1156. 
700. Agabus (Hriglenus) unguicularis, Th. Sk. Col. IX, p. 101.—Ovalis, sat 
convexus, niger, vix supra subzenescens, antennis pedibusque rufis, femoribus 
picescentibus subtilissime reticulatus, nitidus, elytris guttula pone medium 
maculaque apicali pallidis ; elytris punctis subseriatis et apicalibus haud profundis, 
epipleuris basi rufescentibus. Long. 64, lat. 34 m.m. 
There is no difference in the sculpture of the sexes in this species: the male has 
the basal joints of the front and middle tarsi a little incrassate, and furnished 
beneath with short hairs bearing very small palettes; the claws of the front feet 
are short, and the anterior bears a very sharp tooth in the middle beneath. 
Europe, (Sweden, South Finland, Stettin, Berlin, Britain). 757. 
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