480 On Aquatic Carnivorous Coleoptera or DijtiscidcB. 



Mas, subtilissime punctatus, fere opacus ; tarsis anterioribus et intermediis 

 tortiter dilatatis, illis unguiculo anteriore leviter incrassato, intus sinuato. 

 Fern., omnino opaca, fere impunctata. 



North America, (Carolina, Massachusetts, Michigan). 327. 



628. Hjdroporus arcticus, Thorns., M.C — Elongato-ovalis, convexus, crebre 

 pubescens, obsolete punctatus, subopacus, nigricans, pedibus rufis, capite rufescente 

 medio fusco, prothoracis eljtrorumque lateribus indistincte rufescentibus, anteiinis 

 fuscis basi rufo ; subtus sat nitidus, coxis posterioribus sparsiiB obsolete punctatis ; 

 abdomine tantum basi utrinque punctato ; prosterni processu vix compresso, medio 

 sat distincte carinato. Long. 5, lat. 22 m.m. 



Mas, tarsis anterioribus et intermediis fortiter dilatatis, unguiculis anterioribus 

 ad basin abrupte curvatis, fere sequalibus, crassiusculis. 



Lapland ; Arctic Siberia, (ascending to 69^ Nox-th, according to Sahlberg). 332. 



629. Hydroporus kolstromi, Sahl., Not. fenn. XI V, p. 145. — Oblongo-ovalis, 

 elongatus, sat nitidus sparsim sed distincte pubescens, niger, capite, prothoracis 

 lateribus, elytris pedibusque testaceis ; prothorace parvo, elytris angustiore, 

 lateribus leviter curvatis, marginibus crebre punctatis, disco sublsevigato ; elytris 

 elongatis, crebre, fere fortiter punctatis. Long. 5i 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. 



Group 5. 



630. Dytiscus dorsalis, Fab., Hydroporus dorsalis, M.C. — Oblongo-ovalis, evi- 

 denter pubescens et punctatus, colore variabilis, supra saepius nigricans, capite, 

 prothoracis lateribus elytrisque signaturis extemis rufescentibus ; prothorace 

 transverso, 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. 41, 

 lat. 2i m.m. 



