On Aquatic Carnivorous Coleoptera or Dytiscidce. 365 



This species is very similar to Hydroporus cliilensis, but is a good deal smaller 

 and narrower. I have seen only a single individual, for which I am indebted to 

 Herr Steinheil. 



South America, (Achiras). 454. 



312. Bidessus uruguensis, n. sp. — Oblongo-ovalis, nitidus {$), vel opacus (p), 

 obsoletissime punctatus, parcissime brevissime pubescens (fere nudus), fuscus, capite, 

 thorace, antennis pedibusque testaceis, thorace medio infuscato, elytris obsolete et 

 minus late testaceo-signatis ; coxis posterioribus impunctatis. Long, vix 2, lat, 

 1 m.m. 



The fuscous colour by which the elytra are suffused, leave some ill-defined small 

 pale marks. 



The male is shining and has the fine and scanty punctuation of the elytra 

 distinctly visible, while the female is dull and without distinct sculpture : the tarsi 

 of the male are rather broader and shorter than in the female. 



The species is scarcely distinct from some of the varieties of Hydroporus affinis 

 (No. 318), but the male is more obsoletely punctured, and the female has the 

 upper surface dull, without sculpture. 



South America ; Uruguay. 109. 



313. Bidessus nitidus, (Bab). — Oblongo-ovalis, nitidus, nudus, fuscus, capite, 

 thorace, antennis pedibusque testaceis, elytris indeterminate testaceo-signatis, interne 

 crebre fortiter punctatis, lateribus fere impunctatis ; coxis posterioribus medio 

 parce sub-obsolete punctatis. Long. 2, lat. 1 m.m. 



The male has the front and middle tarsi slightly dilated. 



This is extremely closely allied to some of the varieties of Hydroporus affinis 

 (No. 318), but it is a little broader than any of them, and the punctuation of the 

 elytra is coarser and more sparing ; and the few punctures on the coxse are less obso- 

 lete ; it is still more similar to Hydroporus liliputanus (No. 316), but the impression 

 on the elytra is more elongate and the punctures on the coxse fewer and smaller. 



This species was described by Babington under the name of Hydroporus nitidus, 

 but this name cannot be used on account of the prior Hydroporus nitidus, Sturm. 



Brazil. (Petropolis, May and December, 1850 ; Santa Rita, August, 185U, R. F. Sahlberg.) 110. 



314. Bidessus crassus, n. sp. — Brevis, latus, nitidus, nudus, testaceus, pectore 

 abdomineque infuscatis ; elytris indeterminate fusco-punctatis et lineatis, circa 

 suturam basin versus fortiter minus crebre punctatis, lateribus apiceque Isevigatis ; 

 coxis posterioribus omnino Isevigatis. Long. If, lat. 1 m.m. 



This species is distinguished among its immediate allies by its very short, broad 



3 B 2 



