572 On Aquatic Carnivorous Coleoptera or Dytiscide. 
1s equidistant from the suture and the second stria, while the outer one is three 
times farther from the lateral margin than it is from the third stria. The male has 
the front and middle tarsi broadly dilated, the front tibize much bent at the base, 
and very distinctly notched at some little distance below the knee. 
Amazons ; found by Professor Trail in the water standing in the bottom of a canoe in the Rio Sappo, 
21st. Nov., 1874. 650. 
833. Copelatus tibialis, n. sp.—Oblongus, elongatus, angustulus, fere parallelus, 
capite, prothoracis lateribus, elytrorum basi, antennis pedibusque rufis, prothorace 
medio elytrisque vitta sublaterali rufescentibus ; prothorace fere levigato ; elytris 
stris quatuor sat profundis ; antennis subelongatis. Long. 5%, lat. 25 m.m. ~ 
In the male the front and middle tarsi are broadly dilated, and the front tibiee 
are so abruptly bent near the base as almost to appear angulate, and they have a 
very distinct notch on the inner face below the knee ; the female I do not know. The 
species is closely allied to Copelatus prolixus, but is much less elongate, and has 
numerous minor points of distinction; the disposition of the strize on the elytra is 
about the same in the two species, but in the present one they are deeper, and the 
sutural stria seems rather shorter. 
South America, (Brazil.) 651. 
834. Copelatus nitidus, n. sp.—Oblongus, sat elongatus et angustus, minus depres- 
sus, nitidior, niger, elytris castaneis, antennis pedibusque rufis; prothorace parce 
punctulato ; elytris striis quatuor sat profundis, prima (a sutura haud remota) quam 
ceteris paulo longiore. Long. 5%, lat. 27 m.m. 
In the male the front and middle tarsi are moderately dilated, and the front tibize 
are nearly simple; the female I do not know. The only individual I have seen is 
in very bad condition, but the species is a clearly distinct one, the hind coxe being 
shorter and rather different in form from the rest of its allies. In the collection of 
the Brussels Museum there is a specimen which is probably the female of this 
species, but it is considerably smaller, and has the striz of the elytra finer. 
South America (Columbia, coll. de Bonvouloir). 652. 
835. Copelatus guerini, Aube, M.C.—Oblongus, sat angustus, fusco-castaneus, 
capite, prothoracis lateribus elytrorumque basi rufescentibus ; antennis pedibusque 
rufis; prothorace obsoletius punctato; elytris parce obsolete punctulatis, striis 
quatuor clongatis, prima a sutura remota. Long. 5%, lat. 3 min. 
In the male the front and middle tarsi are a good deal dilated, the front tibiz 
are bent below the knee, and their basal part is slender, and is broadly and indis- 
tinctly emarginate below the knee. I have seen only one specimen, in bad condition ; 
