472 On Aquatic Carnivorous Coleoptera or Dytiscide. 
medio sublevi; elytris sat crebre et fortiter punctatis; coxis posterioribus sat 
crebre punctatis. Long. 33, lat. 13 m.m. 
The male has the front tarsi a little broader than the female. This form is 
rather larger and broader than Dytiscus tristis, and has the elytral punctuation and 
pubescence rather stronger, but I think it will scarcely prove to be a distinct 
Species. 
Europe. (Sweden; Finland; Germany ; France, the Somme, Bedell). 355: 
602. Dytiscus tristis, Payk., Hydroporus tristis, M.C.—Oblongus, _ parcius 
pubescens, sat nitidus, nigricans, antennarum basi pedibusque rufis, elytris capiteque 
fusco-rufis, hoc anterius dilutiore ; prothorace basi fortiter punctato, medio subleevi, 
elytris sat subtiliter parcius punctatis; coxis sat crebre, fortiter punctatis. Long. 
3, lat. 14 m.m. 
The sexes in this species are scarcely distinguishable, the male having the tarsi 
only very little broader than in the female. ) 
It is doubtful whether Hydroporus varians, Lec., be distinct from this species or 
not. My two specimens from Massachusetts are rather less elongate, still less 
pubescent, and rather more strongly punctured above, but with the hind coxe 
rather less punctured. Hydroporus ruficapillus, Mann., from Sitkha, can scarcely be 
considered more than a variety of Dytiscus tristis, Payk.; it is slightly more 
elongate, has the surface dull, and the pubescence still less. 
Northern Europe; Siberia; North America. (Sweden; Finland, 69° north, Sahlberg; Scotland ; 
basin of the Seine ; Alsatia; Germany). 354, 
603. Hydroporus neglectus, Schaum, M.C.—Oblongus, angustulus, minus pubes- 
cens, vix nitidus, subtus nigricans, capite anterius rufo, elytris fusco-rufis, prothorace 
fusco, hoe elytris angustiore, medio parcissime punctato ; elytris sparsim subtiliter 
punctatis ; antennis gracilibus fusco-rufis, basi dilutiore ; coxis posterioribus sparsim 
sat fortiter punctatis; tarsorum anticorum articulo 3° elongato. Long. 23, lat. 
13 m.m. 
Mas, tarsis anterioribus et intermediis latioribus, illis unguiculis ineequalibus 
anteriore crassiore, apice fisso. 
Northern and Central Europe. (Sweden, Finland, England, basin of the Seine, Germany). 353. 
604. Hydroporus scalesianus, Steph., M.C.—Oblongo-ovalis, parcissime pubescens, 
nitidulus, ferrugineus, elytris plus minusve fuscescentibus, abdomine pectoreque 
nigricantibus ; prothorace medio impunctato ; elytris parcius vix fortiter punctatis ; 
coxis posterioribus punctis paucis magnis ; tarsorum anticorum articulo 3° elongato. 
Long, 2, lat. 1 m.m. 
