On Aquatw Carnivorous Coleoptera or Dytiscide. 483 
impresso, disco sparsim, limbo fortius punctato, elytris crebre distincte punctatis ; 
coxis posterioribus evidenter punctatis; tarsis articulo 3° magno. Long. 4, 
lat. 2 m.m. 
There seems to be scarcely any distinction between the sexes of this species. 
Europe. In springs among moss on mountains, (Britain, Geneva, Piedmont, Savoy,Tyrol, Styria). 363. 
Group 7. 
637. Hydroporus picicornis, Sahl., Not. fenn. XIV, p. 152.—Oblongo-ovalis, 
fere sine pubescentia, niger, subnitidus, antennis p2dibusque fuscis, illis basi reto ; 
prothorace medio levigato, basi crebre subtiliter punctato; elytris  subtiliter 
punctatis ; coxis posterioribus parce punctatis. Long. 2%, lat. 13 m.m. 
I have seen but a single individual of this species ; 1t is without doubt a male; 
it has the front tibize excised at the base inwardly, and the tarsi broad and parallel, 
with the third joint more developed than in Hydroporus melanarius (No. 555) and 
its immediate allies; the lobes of this joint are however much shorter than they 
are in the species allied to H. morio (No. 598); and the general form and the 
absence of pubescence point out an affinity with H. melanarius. The prosternal 
process 1s very largely developed; and in the structure of the coxal articulation 
the species is allied to H. collaris Lee. 
Europe and Siberia, (Finland, Sahlberg). 399. 
638. Hydroporus collaris, Lece., Hydroporus stagnalis, M.C_—Subovalis, sine 
pubescentia, nitidus, rufescens, abdomine pectoreque nigricantibus; prothorace 
crasse marginato, medio late levi, basi sat crebre punctato ; elytris sparsim 
subtiliter punctatis ; prosterni processu magno, subplano, ad latera evidenter 
marginato, medio nullo modo carinato; coxis posterioribus sparsim punctatis. 
Long. 33, lat. 2 m.m. 
The only individual I have seen is probably a male ; the front and middle tarsi 
are broad, and have the third joint well developed; the front tibize are excised 
at the base inwardly. Though very different in appearance from Hydroporus 
picicornis Sahl. the two species seem closely allied structurally. 
North America, (Lake Superior). 402. 
639. Hydroporus oblitus, Aubé, M.C.—-Ovalis, sine pubescentia, nitidus, rufo- 
castaneus, abdomine pectoreque nigricantibus, antennis pedibusque rufis ; prothorace 
latius levi, basi sat discrete punctato; elytris coxisque posterioribus sparsim 
; 1 | 
punctatis. Long. 33, lat. 13 m.m. 
TRANS. ROY. DUB. SOC., N.S., VOL, Il. 3 R 
