On Aquatic Carnivorous Coleoptera or Dytiscide. 335 
punctured, in fact almost impunctate ; the elytra have a rather coarse, but very 
little impressed and therefore obsolete punctuation ; the more internal of their 
series of punctures can be distinguished at the base only, and the more external 
series are extremely indistinct. 
The species is larger and broader than Hyphydrus rufo-niger, Clk. (No. 218), and 
has the elytra more punctate, but with the inner series of punctures on the other hand 
more indistinct. In form and sculpture it is nearer to Hydrovatus castaneus. 
Motsch., but it is larger and darker, and the margin of the clypeus is less obsolete. 
It is the largest East Indian species here described. I have seen only a single 
individual in bad condition ; it is I believe a female. 
Siam, (Bangkok), Castlenau. 1153. 
920. Hydrovatus bonvouloiri, n. sp.—Ferrugineus, latus, convexus, nitidus, pro- 
thorace crebre punctato ; elytris fortiter sat crebre punctatis ; coxis parcius distincte 
punctatis. Long. 34, lat. 23 m.m. 
Antenne rather long and slender, simple. Clypeus without margin, and very 
slightly emarginate over the labrum. Head completely destitute of sculpture. 
Thorax rather closely and somewhat finely punctured. Elytra with numerous 
scattered, distinct punctures. Coxee very shining and with very distinct but 
sparing punctures. 
India bor, (coll. Bonvouloir). 24. 
9921. Hydrovatus major, n. sp.—Rufescens, supra piceo-rufus, capite, thorace, 
elytrorum maculis dilutioribus; elytris fortiter punctatis, anterius ad latera 
impressione longitudinali profunda. Long. 33, lat. 2% m.m. 
This species is of broad form; the head has very little punctuation, but the 
thorax is rather closely and distinctly punctured ; the elytra are strongly punctured, 
the punctuation being very coarse and close near the sides, and obsolete at the apex, 
a little behind the shoulder near the epipleura there is a deep elongate depression. 
The posterior coxe are very coarsely punctured. 
The species is remarkable by the impressions on the sides of the elytra ; the 
colour of the upper surface is variable, and the red spots on the wing-cases are in 
some instances much more conspicuous than in others. The sexual differences seem to 
be extremely slight ; the antennz are slender and rather short, and in the male are 
slightly more serrate internally than they are in the female ; and in this latter sex 
the punctuation on the wing-cases seems to be just perceptibly denser than it is in 
the 1nale. 
It is closely allied to Hydrovatus horni, Crotch. 
Duenas, Guatemala, G. C. Champion, 1879. 1122. 
