544 On Aquatic Carnivorous Coleoptera or Dytiscidw. 



Group 3. 



767. Agabus undecim-guttatus, Aub^, M.C. — Ovalis, sat latus, subdepressus, 

 pernitidus, subtilissime reticulatus, niger, antennis pedibusque rufis ; supra 

 maculis undecim testaceis, parvulis ; thorace cum elytris omnino continue, basi 

 utrinque ad angulos posteriores baud sinuato, bis subacutis baud retrorsuni 

 spectantibus, margine laterali lato ; prosterni processu lato, piano, apice obtuse. 

 Long. 6i, lat. 4 ra.m. 



The male of this species has a slight incrassation of the front and middle tarsi, 

 and the three basal joints narrow beneath are clothed with short hairs ; the apical 

 ventral segment is quite smooth. There is no sexual difference of sculpture. The 

 yellow marks of the upper surface consist of one on the middle of the head, one on 

 each side of the thorax near the side, (the anterior angle being more or less reddish), 

 and four on each elytron, one at the base near the suture, and another near the 

 shoulder, a third near the side beyond the middle, while the fourth is placed near 

 the apex. The excessively fine sculpture of the elytra consists of reticulations, 

 with a minute puncture in the middle of each mesh. The serial punctures of the 

 elytra are fine but quite distinct. 



South America, (Brazil). 826. 



768. Agabus decemnotatus, Aub^, M.C. — Ovalis, latus, subdepressus, pernitidus, 

 fere omnino laevigatus, subtus piceo-rufus, vel rufus, supra jiiceus, vel nigro-piceus, 

 capite testaceo, utrinque piceo, thorace utrinque late vage testaceo, elytris maculis 

 magnis decern testaceis, thorace cum elytris omnino continue, basi utrinque ad 

 angulos posteriores sinuato, angulis posterioribus acutis, margine laterali sat lato ; 

 prosterni processu lato, plane, apice obtuse. Long. 7, lat. 4i m.m. 



There is very little difference in the sexes of this species, a slight difference in 

 the clothing of the basal joints of the front and middle tarsi being all that dis- 

 tinguish the male. The diminution of the sculpture reaches its extreme in this 

 species, even the marginal punctures of the thorax are extremely fine, while the 

 serial punctures of the elytra can scarcely be distinguished. The yellow spots on each 

 elytra are placed one near the scutellum, one some little distance from the shoulder, 

 one near the suture about the middle, one near the outer margin a little behind 

 the middle, and one near the apex. 



South America, (Cayeune). 827. 



769. Platynectes ernatifrons, n. sp. — Ovalis, sat latus, subdepressus, nitidus, supra 

 densissime subtilissimeque reticulatus, niger, antennis pedibusque rufis, capite in 

 medio testaceo-maculato, thorace ad angulos anterieres rufescente, elytris macula 

 subapicali aliaque parvula sublaterali pone medium testaceis ; thorace basi utrinque 



