On Aquatic Carnivorous Colcoptera or Dytiscide. 279) 
attenuatus, convexus, pernitidus, leete rufo-testaceus, leevis, elytris nigris, maculis 
duabus magnis ad basin, fascia mediali interrupta apiceque testaceis ; abdomine 
utrinque infuscato ; prosterni pectorisque medio et laminis coxarum dense punctatis. 
Long. 2, lat. 13 m.m. 
In the markings of the elytra, the size of the spots varies, so that the yellow 
colour sometimes predominates over the black. 
Japan; China. 479. 
70. Hydrocanthus flavus, Motsch. M.C.—Oblongo-ovalis, posterius acuminatus, sat 
convexus, pernitidus, fulvo-testaceus, elytris fere impunctatis, prosterni pectorisque 
medio et laminis coxarum crebrius punctatis. Long 23, lat. 1§ m.m. 
The small size and pale unvariegate unicolorous surface are the chief characters 
of this species. 
China: Siam, (Bangkok) ; Formosa: (Hast India fide Motschoulsky). 478. 
The specimens from Formosa are larger, and have the sides of the ventral segments infuscate, but I do 
not think it advisable to consider them a distinct species without further evidence. 
I. 10.—Genus HYDROCANTHUS. 
Prosternal process extremely broad, broaderthanlong ; swimming legs very stout. 
Species are found in most of the warmer parts of the world, but not in Kurope.* 
71. Hydrocanthus australasize, Wehncke, Berl. Zeit. 1876, p. 223.—Oblongo- 
ovalis, posterius acuminatus, transversim sat convexus, minus latus, pernitidus, 
niger, antennis rufis, pedibus corporeque subtus piceis, elytris seriebus punctorum 
obsoletis, pone humeris leviter sinuatis; spatio inter coxas anteriores sat lato ; 
prosterni pectorisque medio et laminis coxarum crebrius punctatis. Long. 53, lat. 
25 m.m. 
The only difference between the sexes is the two or three cups on the under side 
of the front tarsi in the male. 
Northern Australia, (Rockhampton). 476. 
72. Hydrocanthus indicus, Wehncke, Berl. Zeit. 1876, p. 223.—Oblongo-ovalis, 
posterius acuminatus, transversim sat convexus, minus latus, pernitidus, castaneus, 
elytris vix perspicue punctatis ; spatio inter coxas anteriores sat lato ; prosterni 
pectorisque medio et laminis coxarum crebre punctatis. Long 5, lat. 25 m.m. 
* In addition to those enumerated in the text, the two following species may be referred, although with 
doubt, to the genus. Hydrocanthus fasciatus, Stein]. (No. 1,325 huj. op.). Hydrocanthus socius, Sahl. 
(No. 1,329) ; both from South America. 
