On Aquatic Carnivorous Colcoptcra or Dtjtiscidce. 279 



attenuatus, convexus, pernitidus, Isete rufo-testaceus, Isevis, elytris nigris, maculis 

 duabus magnis ad basin, fascia mediali interrupta apiceque testaceis ; abdomine 

 utrinque infuscato ; prosterni pectorisque medio et laminis coxaruin dense punctatis. 

 Long. 2f, lat. If 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 crebrlus punctatis. Long 2|, lat. if m.m. 



The small size and pale unvariegate unicolorous surface are the chief characters 

 of this species. 



China : Siam, (Bangkok) ; Formosa : (East India fide Motschoulsky). 478. 



The specimens from Formosa are larger, and have the sides of the ventral segments infuscate, but 1 do 

 not think it advisable to consider them a distinct species Avithout further evidence. 



I. 10.— Genus HYDROCANTHUS. 

 Prosternal process extremely broad, broader than long ; swimming legs very stout. 

 Species are found in most of the warmer parts of the world, but not in Europe.* 



71. Hydrocanthus australasife, Wehncke, Berl. Zeit. 1876, p. 223.— Oblongo- 

 ovalis, posterius acuminatus, transversim sat convexus, minus latus, pernitidus, 

 uiger, 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. 5i, lat. 



2«- 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). 47G. 



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. 2t 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, Steinl. (No. 1,325 huj. op.). Hydrocanthus socius, Sahl. 

 (No. 1,329) ; both fi-om South America. 



