On Aquatic Carnivorous Coleoptera or DytiscidcB. 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 onlj^ a single pair of this remarkable species, the male in the 

 collection of the Genoa Museum, the female in my own. 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 eri'or 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 Madao^ascar C. owas. 



Africa, (Gaboon). 1064. 



Group 3. 



1135. Cybister owas. Lap., Tragus 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 4| 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., TOL. II. t A. 



