350 On Aquatic Carnivorous Coleoptera or Dytiscide. 
260. Bidessus discretus, n. sp.—Oblongo-ovalis, brevis, sat convexus, fere sine 
pubescentia rufo-testaceus, elytris fuscis, signaturis magnis pallide testaceis, 
abdomine plus minusve infuscato; elytris crebrius fortiter punctatis, prothorace 
minus distincte punctato ; coxis posterioribus fortiter punctatis. Long. 2, lat. 
13 m.m. 
The male is shining and has the front and middle tarsi distinctly dilated : of the 
female there are two forms, one similar to the male in sculpture, the other dull and 
with the punctuation of the upper surface more obsolete. The plica (or basal im- 
pression) on the elytra is very distinct, and is about as long as that on the thorax. 
The colour of the elytra is somewhat variable ; the base is fuscous, but a slight 
distance from it there is a very broad pale yellow band, which externally reaches 
as far forward as the shoulder, and internally is interrupted at the suture, across the 
middle there is a dark band which indeed extends nearly to the apex, except that 
there is a very large subapical mark ; the yellow colour, however, at the base and 
apex is sometimes more extensive owing to the comparative obliteration of the 
dark marks. 
North America, (Texas, Belfrage). 1130. 
261. Dytiscus unistriatus, Schranck, Hydroporus unistriatus, M.C.—Ovalis, 
piceus, vel fuscus, vel rufescens, thorace rufescente, subtiliter sed distincte pubescens, 
subnitidus; elytriscrebre, distincte, basi sat fortiter punctatis, stria suturali abbreviata. 
Long. 2, lat. 1 m.m. 
The male has the front and middle tarsi distinctly dilated. There are two forms 
of the female, one is quite dull, and has the punctuation quite obsolete; the other 
differs but little from the male so far as the sculpture is concerned. 
This is a very variable species, the colour is sometimes nearly black, with the 
margins of the elytra, and an interrupted obscure basal fascia pale, the thorax being 
nearly red : sometimes the general colour is of an obscure red with the suture 
slightly darker. In Finland is found a variety which is more shining and less 
pubescent, and has the punctures of the elytra more distinct and distant: I have 
seen from Lanaeken, in Belgium, two specimens closely approaching this Finland 
form. 
Europe, from Lapland to Corsica ; Britain, Belgium, France, Germany. 116. 
262. Hydroporus goudotii, Lap., M.C.—Ovalis, nitidus, tenuissime pubescens, 
antennis, pedibus, capite thoraceque testaceis, hoc basi infuscato; elytris fusco- 
testaceis, signaturis externis indeterminate pallidioribus; crebre punctatis, punctis ad 
basin versus suturam fortioribus ; pectore abdomineque piceis. Long. 1%, lat. 1 m.m. 
I do not see any characters by which the male can be distinguished from the 
