334 On Aquatic Carnivorous Coleoptera or Dytiscide. 
separated, and the hind legs rather more slender. In the male the basal joints of 
the front and middle tarsi 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). Philippines. 21. 
217. Hydrovatus castaneus, Motsch., M.C.— Castaneus, nitidus, convexus, sat 
angustus; prothorace crebre punctato; elytris obsolete punctatis, seriebus puncto- 
rum sat distinctis, coxis parce obsoleteque punctatis. Long. 32, lat. 25 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 
coxee 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 type. 
Ind. or., Burmah. 22. 
218. Hyphydrus rufo-niger, Clark, M.C.—Nigricans, subtus piceus, pernitidus, 
convexus, angustulus; prothorace crebre, subtiliter obsoleteque punctato ; elytris 
fere impunctatis, sed seriebus punctorum impressis distinctis ; coxis parce punctatis. 
Long. 32, 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 antennz are rather long. The 
punctuation of the coxze though sparing is more distinct than in H. castaneus ; and 
the raised margin of the clypeus is not interrupted in the middle. 
Siam, (Bangkok). 23. 
919. Hydrovatus picipennis, Motsch., M.C.—Piceus, subtus diluticr, nitidus, con- 
vexus, robustus, sat latus, prothorace elytrisque crebre subobsolete punctatis, illis 
seriebus punctorum parum distinctis; coxis parce punctatis. Long. 4, lat. vix. 23 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; the upper surface of the head is 
almost impunctate, the antenne 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 
