'666 On Aquatic Carnivorous Coleoptera or Dytiscidce. 



form ; the dark markings on the elytra consist of one or two lines and several spots, 

 or thickened and interrupted lines : the hasal ventral segment of the hind body 

 shows a single series of punctures on each side and elsewhere is quite smooth. 

 The only specimen I have seen is, I think, a female. 



Brazil, (Santa Rila, August, 1850, E. F. Sahlberg). 111. 



315. Bidessus atomarius, n. sp. — Ovalis, angustulus, Isevis, nitidus, impunctatus, 

 rufo-testaceus, elytris infuscatis, pone basin et ad apieem testaceo-signatis. Long, 

 la, lat. Im.m. 



This minute species looks like a Laccophilus. 1 have seen only three individuals, 

 all of which have the front and middle tarsi quite slender. 



Brazil, (Petropolia, May, 1850, R. F. Sahlberg). 112. 



316. Hydroporus liliputanus, Aube. M.C. — Oblongo-ovalis, sat latus, nitidus, 

 fuscus, antennis pedibusque testaceis ; elytris versus suturam crebre sub-obsolete 

 punctatis, stria discoidali impressa ; coxis posterioribus omnino Isevigatis. Long. 

 2, lat. 1 m.m. 



Aube's unique type i.s a little paler than the specimen above described, but 

 otherwise I see not the least difference. 



BrazU, (Bahia). 113. 



3 1 7. Bidessus texanus, n. sp. — Oblongo-ovalis, angustulus, sub-depressus, dense 

 subtilissime pubescens, sub-nitidus, testaceus, abdomine pectoreque nigricantibus, 

 ■elytris sutura fasciisque transversis fuscis, dense subtilius punctatis ; corpore subtus 

 fere irapunctato. Long. \l, lat. 1 m.m. 



This species is very similar in appearance to the European Hydroporus minutis- 

 simus, (No. 267) ; I have seen only two individuals, both of which have the front 

 and middle tarsi quite slender. 



North America, (Texas, scut by Belfrage). 456. 



318. Hydroporus affinis Say, M.C. — Oblongo-ovalis, sat angustus, sat nitidus, fere 

 nudus, fuscotestaceus, pedibus, capite thoraceque testaceis, hoc disco infuscato ; 

 elytris plus minusve distincte pallido-signatis, mediocriter punctatis ; coxis 

 posterioribus medio parce obsolete punctatis, vel Icevigatis. Long. l|, lat. 1 m.m. 



Obs. species statura, pictura, punctatura coloreque corporis variabilis. 



This species is very variable, and I had at first separated the variations as dis- 

 tinct species, but after a repeated study I have been unable to detect any definite 

 characters to distinguish the varieties. 



