480 On Aquatic Carnivorous Coleoptera or Dytiscide. 
Mas, subtilissime punctatus, fere opacus; tarsis anterioribus et intermediis 
fortiter dilatatis, illis unguiculo anteriore leviter incrassato, intus sinuato. 
Fem., omnino opaca, fere impunctata. 
North America, (Carolina, Massachusetts, Michigan). 327. 
628. Hydroporus arcticus, Thoms., M.C.—Elongato-ovalis, convexus, crebre 
pubescens, obsolete punctatus, subopacus, nigricans, pedibus rufis, capite rufescente 
medio fusco, prothoracis elytrorumque lateribus indistincte rufescentibus, antennis 
fuscis basi rufo ; subtus sat nitidus, coxis posterioribus sparsim obsolete punctatis ; 
abdomine tantum basi utrinque punctato; prosterni processu vix compresso, medio 
sat distincte carinato. Long. 5, lat. 23 m.m. 
Mas, tarsis anterioribus et intermediis fortiter dilatatis, unguiculis anterioribus 
ad basin abrupte curvatis, fere equalibus, crassiusculis. 
Lapland ; Arctic Siberia, (ascending to 69° North, according to Sahlberg). 332. 
629. Hydroporus kolstromi, Sahl., Not. fenn. XIV, p. 145.—Oblongo-ovalis, 
elongatus, sat nitidus sparsim sed distinecte pubescens, niger, capite, prothoracis 
lateribus, elytris pedibusque testaceis; prothorace parvo, elytris angustiore, 
lateribus leviter curvatis, marginibus crebre punctatis, disco sublevigato ; elytris 
elongatis, crebre, fere fortiter punctatis. Long. 54 m.m. 
This species is nearer to Dytiscus dorsalis than to any other, but is very distinct, 
it is more elongate in form, and the head wants the complete curved impression 
over the labrum peculiar to D. dorsalis. On the other hand its prosternal process, 
and the shoulders of the elytra, and the very discontinuous outline of the thorax 
with the elytra bring it near the insect mentioned. I have seen only a single 
individual, unfortunately in bad preservation; it appears to be a male; the front 
and middle tarsi are moderately broad ; the claws are wanting in this specimen. 
Lapland. I believe the individual of this remarkable species from which the above description is 
made is the only one yet known; it was found by Kolstrom, and kindly communicated to me by its 
talented describer, Dr. John Sahlberg. 1157. 
Grovpr 5. 
630. Dytiscus dorsalis, Fab., Hydroporus dorsalis, M.C.—Oblongo-ovalis, evi- 
denter pubescens et punctatus, colore variabilis, supra seepius nigricans, capite, 
prothoracis lateribus elytrisque signaturis externis rufescentibus; prothorace 
transyerso, basi quam elytris evidenter angustiore, crebre punctato, basin versus 
utrinque impresso ; antennis fusco-rufis, basi rufo, tenuibus; pedibus crassiusculis ; 
corpore subtus rufo, plus minusve infuscato, abdomine crebre punctato. Long. 48, 
lat. 24 m.m. 
