474 On Aquatic Carnivorous Coleoptera or Di/tisciihe. 



I see nothing to distinguish this from Hydroporus vittula, Er., except that the 

 specimens I have examined are very sHghtly smaller and narrower, and have the 

 punctuation and pubescence very slightly more feeble. 



Northern Europe, Siberia. (Sweden and Finland, 68° North, Sahlbcrg ; Jenisei). 349. 



608. Hydroporus vittula, Er., M.C. — Ovalis, satconvexus, 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 punctate, elytris siit 

 crebre et distincte punctatis ; coxis posterioribus sparsim obsolete punctatis. Long. 

 3J, lat. 1§ 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 slight 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 coxae 

 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, Germanj-, 

 Angara ; British Columbia). 348. 



609. Hydroporus humeralis, Aube, 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 Eequaliter punctate. Long. 

 4i, lat. 2^ m.m. 



3Ias, crebre evidenter punctate, subopaco, tarsis anterioribus et intermediis 

 dilatatis, illis unguiculis longioribus, vix insequalibus (? anteriore paulo longiore). 



Fein., 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, supx'a fuscus, capite 

 protheraceque lateribus rufis, illo vertice utrinque fusco, elytris basi signaturisque 

 externis testaceis, pedibus rufis, antennis rufe-fuscis basi rufo ; coxis posterioribus 

 sparsim punctatis. Long. 4, lat. 2 m.m. 



