456 On Aquatic Carnivorous Coleoptera or Dytiscide. 
Group 4. 
552. Hydroporus occultus, n. sp.—Oblongo-ovalis, angustulus, nitidus, leevis, 
piceus, antennis pedibusque rufis; prothorace fere impunctato; elytris parce 
subtilissime punctatis ; coxis posterioribus sparsim subtiliter punctatis. Long. 33, 
lat. 1 m.m. 
This species may be placed not very far from Hyphydrus memnonius, (No. 558) ; 
but it is a very distinct species, and has the prosternal process more developed than 
in the H. melanarius allies. 
I have seen but a single individual, which is probably a male, the basal joint of 
the intermediate tarsus being rather large. 
Algeria, (Coll. Ott). 400. 
553. Hydroporus occidentalis, n. sp.—Oblongo-ovalis, brevius tenuiter parciusque 
pubescens, sub-opacus, niger, antennis pedibusque fusco-rufis ; prothorace medio 
latius subleevi, limbo minus discrete punctato; elytris sat crebre subtiliter punctatis, 
punctis apicem versus obsoletis; coxis posterioribus sparsim, subtiliter punctatis. 
Long. 33, lat. 1¢ m.m. 
Very closely allied to Hydroporus longicornis, but the extremely scanty pubescence 
is rather more visible, and the punctuation of the elytra is closer, and the antenne 
and legs darker in colour. I have scen only one individual. 
é 
North America, (Lake Labache, British Columbia). 398. 
554. Hydroporus longicornis, Sharp, Ent. Mo. Mag. VI, p. 84.—Oblongo-ovalis, 
fere sine pubescentia, niger, antennis pedibusque rufis, illis gracilibus extrorsum 
seepius infuscatis; prothorace medio subleevi, basi sat crebre punctato, lateribus 
antrorsum minus angustatis ; elytris parce subtiliter punctatis ; coxis posterioribus 
parce minus fortiter punctatis. Long. 3%, lat. 17 m.m. 
This species is closely allied to Hydroporus melanarius, but is rather narrower 
and more elongate, and has the elytra more finely punctured, and the thorax is 
rather differently formed, and the antennz more elongate ; it seems to vary in the 
surface, being sometimes shining, and sometimes quite dull. The sexes are very 
difficult to distinguish. 
Europe, (Finland, Scotland, Wales, Savoy,). 397. 
555. Hydroporus melanarius, Sturm, M.C.—Oblongo-ovalis, fere sine pubescentia, 
niger, vel piceus, antennis pedibusque rufis; prothorace minus punctato, medio 
latius subleevi, basi fere sparsim punctato ; elytris parce punctatis, punctis apicem 
versus obsoletis ; coxis posterioribus parce minus fortiter punctatis. Long. 33, lat. 
17 m.1n. 
