On Aquatic Carnivorous Coleoptera or DytiscidcB. 329 



the antennae of the male are not quite so greatly developed, and the front of the 

 head departs much less from the form of H. cuspidatus ; the punctuation of the 

 elytra is closer and much more distinct. 



Africa, (Gaboon). 10. 



202. Hydrovatus confertus, n. sp. — Brevissimus, latus, brunneus, subopacus, 

 evidenter reticulatus, elytris crebre (fere dense) punctatis ; clypeo medio sub- 

 emarginato. Long. 2t, lat. It m.m. 



Mas, antennis crassiusculis, medio leviter incrassatis. 



Fern., antennis tenuibus simplicibus. 



Smaller than Hyphydrus cuspidatus, very similar to H. clypealis (No. 179), even 

 slightly shorter in proportion to its length ; the whole of the upper and under 

 surface is covered with a fine distinct dense reticulation, which makes it opaaue ; 

 the thorax bears scattered extremely fine punctures, and the elytra are more closely 

 punctured than in the other species of the group, the punctures being rather deep 

 and distinct but not coarse ; the punctures on the coxje are not dense. The margin 

 of the clypeus is very indistinct, and the front of the clypeus appears a little 

 emarginate in the middle. The antennae of the female are about as long as in 

 H. cuspidatus, (No. 180) but considerably thinner than in the same sex of that 

 species. The antennae in the male are a little thinner at the base and apex, 

 but slightly thicker in the middle than in the male of H. cuspidatus. The male 

 tarsi have the basal joint only slightly dilated, with the front claws not elongate, 

 the tibiae are not quite so broad as in H. cuspidatus. 



Siam. 1 3. 



203. Hydrovatus subtilis, n. sp. — Ferrugineus, latus, subtiliter reticulatus, sub- 

 opacus, subtiliter sat crebre punctatus : clypeo obsolete marginato, subtruncato. 

 Long. 2i, lat. li m.m. 



Mas, antennis crassiusculis, medio incrassatis. 



About as large as H. clypealis (No. 179) ; not so broad in the middle as is H. 

 cuspidatus (No. 180), and so more parallel. Very closely allied to H. confertus, 

 but rather larger, and more parallel in form, and the punctuation less close, and 

 the reticulation of the surface less evident ; in the male the tarsi are a good deal 

 broader and the antennae are a little longer and stouter, and there is an increase 

 in the size of the joints towards the extremity, commencing at the sixth joint, the 

 fifth and sixth joints are however only slightly enlarged, but the seventh and eighth 

 are much more distinctly so, the ninth is a good deal narrower than the eighth. 



Siam. U. 



