On Aquatic Carnivorous Coleoptera or Dytiscidce. 275 



52. Hydrocanthus semperi, Wehncke, Berl. Zeit. 1876, p. 223.— Ovalis, sat 

 couvexus, posterius atteuuatus, pernitidus, niger, capite protlioraceque ad angulos 

 anteriores rufo-testaceis, illo posterius infuscato ; antennis testaceis, pedibus obscure 

 rufis. Long. 2| m.iii., lat. Ih m.m. 



This is a small and rather short species, distinguished from H. luctuosus (No. 60) 

 and allies by the unspotted elytra. 



Philijipiiie islands ; Luzon. G14. 



53. Canthydrus arabicus, n. sp. — Breviter ovalis, convexus, posterius attenuatus, 

 pernitidus, piceus, capite protlioraceque lataribus testaceis ; elytris guttula parva 

 pone medium testacea, omnino Itevigatis ; antennis testaceis, pedibus rufis. Long. 

 3*, lat. If m.m. 



This species is very closely allied to Hydrocanthus guttula (Xo. 54), but is rather 

 smaller, and besides the colour differences, is remarkable for being without any 

 punctures on the wing-cases. Immature individuals are entirely yellow. 



Arabia, (Hedjaz, Millingen). lliT. 



54. Hydrocanthus guttula, Aube, M.C. — Ovalis, convexus, posterius attenuatus, 

 pernitidus, niger, capite anterius, thoraceque ad angulos anteriores rufo-testaceis ; 

 elytris guttula parva pone medium testacea, punctis sparsis sat conspicuis ; antennis 

 testaceis; pedibus rufis, posterioribus magis obscuris. Long. 3, lat. 15 m.m. 



This species is broader and more convex than Hydrocanthus notula (No. 55), 

 and has the yellow colour at the anterior angle of the thorax much less extended ; 

 the punctures on the elytra are more conspicuous. 



Madagascar ; Mauritius. 490. 



55. Hydrocanthus notula, Er. M.C. — Ovalis, sat convexus, posterius attenuatus, 

 pernitidus, niger, capite anterius, prothoracisque lateribus rufo-testaceis, elytris 

 guttula parva pone medium testacea ; antennis testaceis, pedibus rufis, posterioribus 

 magis obscuris. Long. 3g^, lat. l| m.m. 



The red colour on the head and thorax, is more extended in the male than in the 

 female ; there is sometimes a minute yellow dash at the base of the elytra close to 

 the outer marofin. 



o 



Egypt ; Tangier ; (Angola fide Erichson). 489. 



56. Canthydrus ornatus, n. sp. — Ovalis, sat convexus, posterius attenuatus, 

 pernitidus, niger, capite, prothoracis lateribus, elytrorum macula humeral! aliaque 



TRANS. ROT. DUB. SOC, U.S. VOL, II. 3 



