On Aquatic Carnworous Coleoptera or Dytiscide. 329 
the antenneze 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. 24, lat. 13 m.m. 
Mas, antennis crassiusculis, medio leviter incrassatis. 
Fem., 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 opaque ; 
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 coxe 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 antenne 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 antenne 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 rot elongate, 
the tibiz are not quite so broad as in H. cuspidatus. 
Siam. 13. 
203. Hydrovatus subtilis, n. sp.—Ferrugineus, latus, subtiliter reticulatus, sub- 
opacus, subtiliter sat crebre punctatus: clypeo obsolete marginato, subtruncato. 
Long. 23, lat. 13 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 antenne 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. 14. 
