On Aquatic Carnivorous Coleoptera or Dytiscide. 437 
Group 1. 
495. Hydroporus aulicus, Aubé, M.C.—Oblongo-ovalis, posterius angustatus, 
sparsim subtilissime pubescens, nitidulus, brunneo-ferrugineus, elytris fasciis duabus 
transversis maculaque apicali testaceis; corpore sat crebre et fortiter punctato. 
Long. 6, lat. 3 m.m. 
I have seen only two individuals of this large and remarkable species; they are 
both in very decayed condition, but appear to be of different sexes, although the 
distinctions are but slight; in the male the front tarsi are just distinctly broader 
than in the female, and the fourth joint is a little longer, and its anterior claw is 
incrassate. In each sex the antennze are quite slender, but those of the male are 
distinctly longer than those of the other sex. 
The species is remarkable from its large size, and peculiar form, the head being 
broader than usual, and by its quite distinctly separated hind coxal cavities; the 
margin of the thorax is very broad. 
North America, (from Dejean’s collection). 271. 
496. Hydroporus diversicornis, n. sp.—Ovalis, sat angustus, parcius subtiliter 
pubescens, sat nitidus, ferrugineus, prothorace antice et postice elytrisque sutura 
signaturisque transversis fuscis; prothorace haud tenuiter marginato; elytris sat 
crebre et sat fortiter punctatis; coxis posterioribus sat crebre fortiter punctatis, 
nitidis. Long. 43, lat. 27 m.m. 
Mas, tarsis anterioribus et intermediis bene dilatatis, antennis majusculis, 
articulis intermediis crassioribus. 
The male is a little larger than the female, and besides the antennal development, 
has all the legs thicker than in the female. The claws of the front tarsi are 
almost equal, and differ but little from those of the female. 
This species was sent me by Dr. Leconte as being the H. aulicus, but it is quite 
distinct from that remarkable species and connects it with the H. concinnus group : 
the coxal cavities are contiguous, though scarcely absolutely so; the coxal lines 
are approximate and not bent outwards in front, but at the apex are more divergent. 
North America, (Texas). 288. 
497. Hydroporus concinnus, Lec., M.C.—Ovalis, subtilissime pubescens, nitidulus, 
fere impunctatus, testaceus, abdomine pectoreque nigricantibus, prothorace anterius 
et posterius elytrisque infuscatis, his fasciis latis, vagis, interruptis testaceis ; 
elytris stria suturali sat distincta ; coxis posterioribus sat crebre obsolete punctatis. 
Long. 32, lat. 13 m.m. 
The only individual I have seen is no doubt a male, as it has the front tarsi 
moderately dilated. 
