On Aquatic Carnivorous Coleoptera or Dytiscide. 723 
hind tarsus is largely developed in comparison with the allied species. The male is 
considerably broader than the female, and has the sides of the thorax a little 
explanate. 
Although this species resembles superficially in each sex the Mauritian variety of 
the preceding species, it is perfectly distinct therefrom; the male has the sexual 
pubescence of the intermediate tarsi and their claws quite different ; and the sculp- 
ture of the female though superficially similar is really quite different. 
I have seen only a single pair of this remarkable species, the male in the 
collection of the Genoa Museum, the femalein myown. I purchased my specimen 
from a dealer some years ago, and the Genoa Museum specimen was obtained from 
the same source ; although both specimens are labelled as being from the Gaboon, I 
suspect an error of locality, and believe they may be from Madagascar ; the two 
individuals are old worn specimens and have been pinned two or three times, this 
of itself makes an error probable ; while the sexual characters are approached only 
by the Madagascar C. owas. 
Africa, (Gaboon). 1064. 
Group 3. 
1135. Cybister owas, Lap., Trogus owas, M.C.—Grandis, ovalis, latus, convexus, 
supra olivaceo-niger, subtus niger ; pedibus nigris, femoribus anterioribus et inter- 
mediis basi apiceque, et tibiis anterioribus plus minusve rufescentibus. Long. 
36—40 m.m., lat. 20—22 m.m. 
The male of this species has the front tarsi very large and highly developed, and 
attaining as great a length as 42 m.m. in the transverse direction, the fringing 
hairs even at the base are highly developed and regular, and the pubescent area is 
large ; on the intermediate feet the basal joint bears a large elliptical patch of very 
dense short sexual pubescence, and there may occasionally be a very minute patch 
of similar pubescence on the following joint, the claws are rather elongate and but 
little curved, the anterior one being a little longer and much thicker than the 
other. 
The female has a highly developed sexual sculpture, the occiput being covered 
with scratches, which on each side near the eye extend much forward, the thorax 
is also very much sculptured with scratches, these however become scanty or 
wanting on the middle, the elytra on their basal portion bear deep elongate scratches, 
which however scarcely, or very slightly only, anastomose here and there; at the 
base these scratches reach from the scutellum to the shoulder, they extend rather 
more than half way of the length of the wing-case, and almost immediately behind 
the scutellum they begin to diverge from the suture, so that they cover in fact a 
TRANS. ROY. DUB. SOC., N.S., VOL. II. 5A 
