334 On Aquatic Carnivorous Coleojjtera or Dytiscidce. 



separated, and the hind legs rather more slender. In the male the basal joints of 

 the front and middle tai'si are a good deal more dilated than in the female, but are 

 not so broad as in the corresponding sex of H. nigricans. 



The only specimen I have seen from the Philippine Islands was sent me by Herr 

 Wehncke, it appears to agree entirely with the Australian individuals. 



Australia, (Cape York, Rockhampton). PLUipiiines. 21. 



217. Hydrovatus castaneus, Motsch., M.C. — Castaneus, nitidus, oonvexus, sat 

 angustus ; prothorace crebre punctato ; elytris obsolete punctatis, seriebus puncto- 

 rum sat distinctis, coxis parce obsoleteque punctatis. Long. Si, lat. 2i m.m. 



This species is very convex, and rather narrow in proportion. The clypeus is 

 without distinct raised margin, and a good deal emarginate over the labrum ; the 

 punctures on the thorax are distinct and rather dense about the middle : the punc- 

 tuation of the elytra is more sparing and indistinct than that of the thorax. The 

 hind trochanters are moderately widely separated, and the punctuation of the 

 coxae is very scanty and rather indistinct. 



A specimen sent from Celebes (Macassar, Jan., 1874, Beccari) is rather more 

 distinctly punctured, while one from Rangoon, (Wehncke), is smoother than the t3'pe. 



Ind. or., Burmah. 22. 



218. Hyphydrus rufo-niger, Clark, M.C. — Nigricans, subtus piceus, pernitidus, 

 oonvexus, angustulus ; prothorace crebre, subtiliter obsoleteque punctato ; elytris 

 fere impunctatis, sed seriebus punctorum impressis distinctis ; coxis parce punctatis. 

 Lonsf. 3i, lat. 2 m.m. 



The most shining and most indistinctly punctured, and comparatively the narrowest 

 (with the exception of the little H. parallelus), of all the species. Very closely 

 allied to Hydrovatus castaneus, Motsch. The antennce are rather long. The 

 punctuation of the coxte though sj^aring is more distinct than in H . castaneus ; and 

 the raised margin of the clypeus is not interrupted in the middle. 



Siam, (Bangkok). 23. 



219. Hydrovatus picipennis, Motsch., M.C. — Piceus, subtus dilutior, nitidus, con- 

 vexus, robustus, sat latus, prothorace elytrisque crebre subobsolete punctatis, illis 

 seriebus punctorum parum distinctis; coxis parce punctatis. Long. 4, lat. vix. 2^ m.m. 



In this species, although the front margin of the head is but little distinct, it is 

 more defined in the middle than at the sides ; tlie upper surface of the head is 

 almost impunctate, the antennse are rather long and slender, their shortest joint 

 (the tenth), being much longer than broad. The thorax has a distinct though 

 rather ill-defined punctuation on the disc, but at the sides it is most obsoletely 



