On Aquatic Carnivorovs Coleoptera or Dytiscidce. 369 



324. Bidessus discoidalis, n. sp. — Oblongo-ovalis, ferrugineo-testaceus, nitidus, 

 nudus, elytris testaceo nigroque liiieatis, prothoracis marginibus anterioribus et 

 posterioribus anguste nigricantibus ; elytris crebre, subtiliter, sed distincte et 

 sequaliter punctatis, stria discoidali iinpressa ; coxis posterioribus laevigatis, ab- 

 dominis segmentis basalibus utrinque fortiter punctatis. Long. 3, lat. ll 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, Lee. (No. 321) 

 but is very much broader. 



South America, (Parana). 108. 



325. Hydroporus duponti, Aube, M.C. — Oblongo-ovalis, niger, supra in capita, 

 thorace et elytris signaturis testaceis ; prothorace elytris angustiore, lateribus 

 versus basin fere angustioribus, utrinque striola obliqua jjrofunda 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. 1? 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). 1132. 



r. 23.— Genus HUXELHYDRUS. 



Prosternal process elongate, parallel-sided ; intercoxal process of metasternum 

 not attaining the mesosternal fork ; hind tibiae 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 snbtiis 

 dense sequaliter subtiliterque punctato. Long 3i, m.m., lat. !« m.m. 



I have seen only three individuals of this small but most interesting insect ; one, 



