526 On Aquatic Carnivorous Coleoptera or Dytiscide. 
736. Dytiscus arcticus, Payk., Agabus arcticus, M.C.—Ovalis, angustulus, supra 
minus convexus, minus nitidus, subtus nigricans, capite prosternoque ex parte 
testaceis, supra fusculus, capite anterius, prothorace lateribus vittaque transversa 
in medio, elytris lateribus, antennis pedibusque testaceis ; supra undique conspicue, 
crebrius, irregulariter reticulatus; prothorace margine laterali persubtili. Long. 7, 
lat. 83$ m.m. 
The male has the front and middle tarsi much incrassate, and furnished beneath 
with large quite circular palettes, which appear to be seated directly on the tarsus 
and are about ten or twelve in number: the front claws are unequal, the posterior 
one being rather elongate, and slender and sinuate beneath, while the anterior one 
is rather shorter, and has the basal half thickened so as to form an angular pro- 
jection beneath. The scratches on the upper surface are very deep in the female, 
and in this sex there is generally, but not always, a peculiar sinuation of the sides 
of the thorax just behind the front angles. 
The colour varies somewhat. 
Northern Europe ; Arctic Siberia; (North America, teste Crotch). Sweden; Finland to 69° north, 
Sahlberg ; Scotland ; Alsatia, (coll. Castlenau). 794. 
737. Dytiscus sturmi, Gyll., Agabus sturmi, M.C.—Ovalis, sat convexus, minus 
nitidus, nigricans, supra fuscus, capite thoraceque subzenescentibus, hujus elytro- 
rumque lateribus testaceis, antennis pedibusque testaceis, femoribus medio 
nigricantibus; supra undique subtiliter crebre reticulatus; prothorace margine 
laterali subtili. Long. 8, lat 43 m.m. 
The male has the front and middle tarsi a great deal incrassate, and furnished 
beneath with large palettes which are about twelve in number ; the front claws are 
rather elongate and of about one length and the anterior one is nearly straight 
beneath ; the apical joint of the middle tarsus is very elongate: there is no differ- 
ence of sculpture in the sexes. F 
The colour is subject to some variation. 
Europe ; (Sweden; Finland to 63° North, Sahlberg ; Britain, France, Belgium, Germany). 795. 
Group 18. 
Swimming legs highly developed, short and incrassate; prosternal process rather 
broad, but a good deal compressed; wings of metasternum moderately large; male 
front tarsi much incrassate, furnished beneath with rather long hairs, bearing rather 
well developed palettes, claws rather short. 
One Japanese species. 
