On Aquatic Carnivorous Coleoptera or Dytiscide. 369 
324. Bidessus discoidalis, n. sp.—Oblongo-ovalis, ferrugineo-testaceus, nitidus, 
nudus, elytris testaceo nigroque lineatis, prothoracis marginibus anterioribus et 
posterioribus anguste nigricantibus ; elytris crebre, subtiliter, sed distincte et 
eequaliter punctatis, stria discoidali impressa; coxis posterioribus levigatis, ab- 
dominis segmentis basalibus utrinque fortiter punctatis. Long. 3, lat. 14 m.m. 
The only specimen I have seen of this species has the tarsi quite slender and 
is probably a female. It seems to be allied to Hydroporus pullus, Lec. (No. 321) 
but is very much broader. 
South America, (Parana). 108. 
325. Hydroporus duponti, Aubé, M.C.—Oblongo-ovalis, niger, supra in capite, 
thorace et elytris signaturis testaceis ; prothorace elytris angustiore, lateribus 
versus basin fere angustioribus, utrinque striola obliqua profunda impresso, inter 
striolas transversim depressiusculo; elytris versus suturam crebre fortiter, versus 
latera obsolete, punctatis; corpore subtus nitido, coxis posterioribus fortiter 
punctatis. Long. 3 m.m., lat. 13 m.m. 
I have seen only a single individual—one of Aube’s types—of this very distinct 
species; I do not know its sex, the tarsi are not dilated, but the last ventral 
segment is prominent at the apex and foveolate. The form recalls Huxelhydrus 
syntheticus. The yellow marks on the upper surface are, a transverse line on the 
vertex, a yellow band across the thorax near the front, interrupted in the middle, 
and four or five, small, isolated markings on the elytra, all distant from the suture. 
Brazil, (Coll. Mnizech). 11382. 
I. 23.—Genus HUXEHLHYDRUS. 
Prosternal process elongate, parallel-sided ; intercoxal process of metasternum 
not attaining the mesosternal fork ; hind tibize with a distinct, slender, basal portion. 
Coxal lines shorter than the prosternal process. 
A single species, (and of that only two or three individuals) is known. 
326. Huxelhydrus syntheticus, n. sp.—Niger, antennis pedibusque rufis, capite 
piceo, thorace elytrisque testaceis, thorace marginibus anterioribus et posterioribus 
nigricantibus, elytris indeterminate nigro-lineatis, dense obsolete punctatis, apice 
subtruncatis, utrinque obtuse angulatis, stria discoidali impressis ; corpore subtus 
dense zequaliter subtiliterque punctato. Long 34, m.m., lat. 13 m.m. 
I have seen only three individuals of this small but most interesting insect ; one, 
