On Aquatic Carnivorous Coleoptera or Dytiscidce. 661 



This species has the black irrorations on the elytra smaller and less numerous 

 than most of the allied species, and the longitudinal patch of black along the suture 

 is therefore very conspicuous, in front it just reaches the extremity of the scutellum, 

 but disappears some distance before the apex of the wing cases. 



There seems to be very little variation. 



Madagascar, Arabia. 1016. 



1030. Hvdaticus matruelis, Clk., M.C. — Ovalis, sat elongatus, subtus ferrugineus, 

 supra testaceus, vertice prothoraceque basi in medio nigris, elytris nigro-irroratis, 

 fascia mediali irregulari transversa nigra, ante apicem fascia altera parum dis- 

 tincta, antennis pedibusque anterioribus testaceis. Long. 13, lat. 7 m.m. 



On the front tarsus of the male the fringing hairs are highly developed, and the 

 basal palettes are very much larger than the outer ones. The female has on the 

 lateral parts of the thorax some isolated, short coarse impressions. 



This species is a good deal like the Australian H, cousanguineus (No. 1037), but 

 is very much larger ; it is a rather elongate and but little convex species, and appears 

 to be somewhat variable in colour; it has sometimes a dark mark on the head 

 between the eyes, which at other times is scarcely to be detected ; the medial 

 black fascia on the wing cases is not placed at all behind the middle ; the posterior 

 fascia is very indistinct : the thoracic sculpture of the females is also somewhat 

 variable. 



Western Africa, (Cape Coast Castle). 1015. 



1031. Hydaticus concolor, n. sp. — Minor, angustulus, ovalis, nitidus, nigro-piceus, 

 supra niger, capite anterius et in medio verticis rufescente, elytris versus latera 

 pone medium macula rufa, antennis pedibusque anterioribus rufis ; pedibus pos- 

 terioribus gracilibus, tarsorum marginibus postice breviter ciliatis. Long. 9, lat. 

 4f m.m. 



The male has no fringing hairs on the heel of the front tarsus, and the basal 

 palettes are scarcely larger than the others. I have not seen the female. 



This peculiar little species is most like rlie dark form of H. fabricii (No. 1035), 

 but is smaller and narrower*, it has the upper surface densely and more distinctly 

 punctured than in the allies, and the hind legs are comparatively elongate and 

 slender, with short cilise on the hind margins of the posterior tarsi ; it has a good 

 deal the appeai'ance of a very minute Cybister, but I cannot find any structural 

 characters to distinguish it from the allies near which I have placed it. 



Cochin China. 101 4. 



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