On Aquatic Carnivorous Coleoptera or Dytiscide. 281 
pernitidus, capite thoraceque rufis; elytris iridescenti-nigricantibus, sericbus 
punctorum distinctis, lateribus pone humeros profundius excavatis ; corpore subtus 
rufo-obscuro, capite thoraceque dilutioribus, prosterni processu latissimo. Long. 
4%, lat. 25 m.m. 
Verysimilar toHydrocanthus texanus, but larger and much moreconvex, and with 
the thorax more dilated so that the elytra are more excavate at the sides, and the 
prosternal process is broader. In the male the prosternal process is closely and finely 
punctured and a little hollowed in the middle ; while in the female it is flat, shining 
and impunctate. 
I have not seen any specimen of this species from Mexico, and there is thus some 
doubt whether it is really the H. atripennis, Say, which was described from Mexican 
individuals. 
Brazil, (Santa Rita, September, 1850; Boa Sorta, November, 1850, Sahlberg) ; (Mexico fide Say). 496. 
78. Hydrocanthus debilis, n. sp.—Ovalis, sat convexus, pernitidus, castaneo- 
testaceus, elytris indistincte undulatim fusco-variegatis, fere omnino impunctatis. 
Long. 33, lat. 25 m.m. 
The small size readily distinguishes the species from its allies as yet known to 
me: theelytraappear at first to be concolorous, but when opened are seen to be 
variegate by very undulated fuscous marks. The male has the prosternal process 
densely and finely punctured, and a little impressed, while in the female it is fiat, 
and is coarsely and not densely punctured. 
South America ; Bahia ; Amazon’s Valley. 497. 
79. Hydrocanthus funebris, Fairm. Ann. Soc. Fr. 1869, p. 187.—Ovalis, pos- 
terlus acuminatus, sat latus, pernitidus, niger, pedibus piceis, antennis rufis ; elytris 
seriebus tribus obscuris punctorum, lateribus sat sinuatis, spatio inter coxas anteriores 
sat lato; prosterni pectorisque medio et laminis coxarum sat crebre punctatis. 
Long. 64, lat. 834 m.m. 
There is but little difference between the sexes of this species ; the male has two 
or three cups on the under side of the second and third joints of the front tarsi. 
Madagascar, 475. 
80. Hydrocanthus advena, n. sp.—Minus latus, convexus, pernitidus, piceus, 
antennis rufis ; elytris pone humeris vix sinuatis, subleevigatis ; spatio inter coxas 
anteriores lato, haud elevato; prosterno impunctato ; coxarum posticarum parte 
elevata crebre punctata. Long. 53 m.m., lat. 23 m.m. 
Basscterre (? Guadeloupe). The only individual I have seen is in the collection of the Musée Royal 
at Brussels, and is labelled “ Basseterre ” I am not at all sure what locality is thus intended. 474. 
