A74 On Aquatic Carnivorous Coleoptera or Dytiscide. 
I see nothing to distinguish this from Hydroporus vittula, Er., except that the 
specimens I have examined are very slightly smaller and narrower, and have the 
punctuation and pubescence very slightly more feeble. 
Northern Europe, Siberia. (Sweden and Finland, 68° North, Sahlberg ; Jenisei). 349. 
608. Hydroporus vittula, Er., M.C.—Ovalis, sat convexus, sat crebre pubescens, 
subopacus, subtus nigricans supra fusculus, capite fusco-rufo, prothoracis lateribus 
anguste elytrisque signaturis externis et basali vage testaceis, pedibus sordide rufis, 
antennis fuscis basi rufo ; prothorace sat fortiter minus crebre punctato, elytris sat 
crebre et distincte punctatis ; coxis posterioribus sparsim obsolete punctatis. . Long. 
34, lat. 13 m.m. 
The male has the tarsi distinctly dilated, but the two claws of the front ones are 
nearly similar; it has also a very slieht difference in sculpture from the female. 
The species is closely allied to H. incognitus (No. 611), but is smaller and narrower, 
has the head and the sides of the thorax more obscure in colour, and the hind coxze 
less distinctly punctured. It is still closer to the preceding species, of which indeed 
I expect it will prove a variety. 
Northern Europe; Eastern Siberia ; North America. (Sweden, Finland, Britain, France, Germany, 
Angara ; British Columbia). 348. 
609. Hydroporus humeralis, Aubé, M.C.—Oblongo-ovalis, minus convexus, crebre 
subtiliter pubescens, subtus niger, supra fuscus, prothorace lateribus, elytrisque basi 
signaturisque externis testaceis, capite fusco, vertice epistomateque rufescentibus, 
pedibus rufis, antennis fuscis, basi rufo ; prothoracis disco zequaliter punctato. Long. 
At, lat. 23 m.m. 
Mas, crebre evidenter punctato, subopaco, tarsis anterioribus et intermediis 
dilatatis, illis unguiculis longioribus, vix inzequalibus (? anteriore paulo longiore). 
Fem., per-opaca, omnino obsolete punctata. 
I have seen only one male (in very bad state) of this species : the sexual disparity 
is very marked, the difference in sculpture extending to the under as well as the 
upper surface. 
North America. (Russian America and British Columbia), 347. 
610. Hydroporus ionicus, Mill., M.C_—Ovalis, elongatus, convexus, sat nitidus, 
crebre pubescens, distincte punctatus, subnitidus, subtus niger, supra fuscus, capite 
prothoraceque lateribus rufis, illo vertice utrinque fusco, elytris basi signaturisque 
externis testaceis, pedibus rufis, antennis rufo-fuscis basi rufo; coxis posterioribus 
sparsim punctatis. Long. 4, lat. 2 m.m. 
