522 On Aquatic Carnivorous Coleoptera or Dytiscide. 
728. Dytiscus elongatus, Gyll., Agabus elongatus, M.C.—Oblongo-ovalis, angustulus, 
niger, supra fusco-subeeneus, antennis pedibusque testaceis, femoribus plus 
minusve infuscatis; elytris omnino densissime , subtilissimeque reticulatis, sat 
nitidis ; prothorace lateribus haud curvatis, margine laterali subtili. Long. 7, lat. 
34 m.m. 
In the male the front tarsi are peculiar in form, the basal joint is a little thickened 
at its extremity, but the hairs on it and the following two joints are very little 
indeed, the fifth joint is elongate, and is underneath incrassate about the middle, 
the claws are elongate, and at the base abruptly bent, especially the hinder one, 
they are without tooth, but are a uttle sinuate. The intermediate tarsi have the 
basal joint a good deal thickened, it and the two following ones bearing a few 
extremely short and indistinct glandular hairs. There is no difference in the 
sculpture of the sexes. 
The antenne of this species have a peculiarity, (pointed out by C. J. Thomson) 
which is not however very conspicuous ; they have the 6th to 9th joints a little 
thickened at the extremity at the lower angle; this is more conspicuous in the 
male than it is in the female, and the prominent spot in the former sex seems to 
be a fovea filled with a glandular pubescence. 
Northern Europe ; (Sweden, and Finland to 64°, according to Sahlberg). 765. 
Group 16. 
Prosternal process compressed on its apical half or through its whole length, 
finely but quite distinctly margined ; wings of metasternum large, or moderately 
large ; swimming legs moderately short ; reticulation of upper surface frequently 
very conspicuous ; male front tarsi much incrassate and dilated, their claws various, 
either short and dentate beneath, or elongate, or very elongate. 
Seven species, six of them North American, and one North European. 
729. Agabus reticulatus, Aubé, Spec. p. 355.—Ovalis, sat convexus, niger, 
elytris fuscis vel fusco-nigris, limbo externo rufescente, prothorace ad latera anguste 
minus distincte rufescente, antennis pedibusque rufis, posterioribus piceis ; supra 
undique evidenter reticulatus, vel sat nitidus (¢) et reticulis sat magnis, vel sub- 
opacus (f) et reticulis haud magnis. Long. 8, lat. 45 m.m. 
The male has the basal joints of the front and middle tarsi a great deal incrassate, 
and broadly furnished beneath with hairs of which the terminal half bear three 
