. On Aquatic Carnivorous Coleoptera or Dijtiscidce. 327 



195. Hydrovatus sumatrensis, n. sp. — Brevis, sat latus, nitidus, piceus subtus 

 dilutior, antennis pedibusque testaceis, sat crebre minus fortiter punctatus ; antennis 

 tenuibus simplicibus ; coxis posterioribus fortiter sed minus crebre subinsequaliter 

 punctatis. Long. 2h, lat. iS, m.m. 



This species is not quite so clo.sely punctured on the hind coxae as H. tusculus, 

 and H. fasciatus, to which it is extremely closely allied, and it is also darker in 

 colour. I detect no distinct sexual differences. 



Sumatra, (ten individuals sent by Welmcke). 447. 



19G. Hydrovatus ovalis (Wehncke), n. sp. — Ovalis, brevis, sat latus, minus con- 

 vexLis, subnitidus, castaneo-ferrugineus, elytris basi sat crebre, subtiiiter punctatis ; 

 antennis sat crassis, coxis joosterioribus dense fortiter punctatis. Long. vix. 2+, lat. 

 11 m.m. 



The antennae are rather stout, but are simple and not elongate. The surface of 

 the thorax and elytra although little shining, is not evidently coriaceous ; the 

 punctuation of the thorax is very fine, and that of the elytra is also rather fine. 



Australia, (Brisbane). 156. 



197. Hydrovatus sordidus, n. sp. — Brevis, latus, nitidus, sat convexus, po.stice 

 acuminatus, testaceo-ferrugineiis, elytris magis castaneis, confertim subtiiiter 

 punctatis ; antennis tenuibus, simplicibus. Long. 2i, lat. If m.m. 



Very similar to Hydrovatus simplex (No. 183), hardly as large, slightly broader 

 in proportion, rather less convex, with the punctuation of the upper surface finer, 

 the autennte scarcely more slender and about the same length ; the front tibiae are 

 rather more slender than in H. cuspidatus (No. 180), and the punctuation of the 

 under surface is less dense and distinct. Also very similar to Hydrovatus fusculus, 

 but larger, broader, and less convex, the outline more acuminate and prolonged in 

 its hinder part, the front legs rather broader, and the antennae a little longer. 



I have examined twelve individuals, but find no differences by which I can with 

 certainty distinguish the sexes. 



Mesopotamia, Egypt, Arabia (El Hedjaz). 8. 



198. Hydrovatus humilis, n. sp. — Brevis, sat latus, convexus, vix nitidus, 

 castaneus, elytris magis fuscis, sat crebre punctatis ; antennis vix tenuibus ; coxis 

 posterioribus crebre punctatis. Long. 21, lat. It m.m. 



Very similar to Hydrovatus simplex, (No. 183), but rather narrower, not so 

 shining, and with the elytra not quite so coarsely punctured, and the front tibiae 

 rather more slender. The only two individuals I have seen have the tarsi quite 



