658 On Aquatic Carnivorous Coleoptera or Dytiscida. 



This peculiar species has the colour of a Dineutes a genus of Gyrinidre, and 

 resembles a good deal some of the broader of those species in its form, except that 

 it has the thorax shorter. I can find no structural character however to distino'uish 

 it from the species of H3'daticus, although it has the epipleurte of the elytra broader. 



The only individual I have seen is a female and has no sculpture likely to be 

 peculiar to its sex. The whole of the upper surface is dull and appears without 

 scu]))ture, it is however very minutely punctured, the three series of punctures on 

 the wing-cases can be seen, the inner however is the only one that is distinct, 

 and the outer can scarcely be detected even with a very careful examination. 



Borneo. (Sarawak, found by the Mart[iiis J. Doria in 1865-'66, Genoa Mus.) 1023. 



1024. Hydaticus Havolineatus, Boh., M.C. — Major, robustus, ovalis, subtus 

 ferragineus vel piceus, supra capite thoraceque rufo-testaceis, illo vertice longe, 

 hoc in marginibus anterioribus et posterioribus nigris ; elytris ex parte majore 

 nigris, sed fascia pone basin transversa testacea, et colore nigro a lineis testaceis in 

 lineas longitudinales nigras diviso, lineis his nigris prtesertim versus latera et ad 

 apicem ab irrorationibus compositis. Long, 18, lat. 10 m.m. 



The fringing hairs of the front tarsi of the male are moderately long, and tlie 

 palettes are large those at the base being specially large. Tlie female has a patch of 

 rather fine net-like impressions on each side of the thorax at some distance from 

 the outside. 



This species is conspicuous from its large size, and by the large extent of the 

 black colour on the back of the head ; this black colour is transversely almost 

 rectilinear in front and sliows no ti'ace of including any paler marks. 



According to the individuals before me it is a variable species, sometimes being 

 much broader than at others ; the specimens from Natal are of rather narrow and 

 elongate form, with the yellow lines of the elytra distinct although irregular ; the 

 individuals from Arabia and Lake Nyassa ai-e broader, and the black colour on the 

 elytra has more obliterated tiie yellow lines on the apical portions of the elytra, 

 and the female has no peculiar sculpture on the thorax. The individual from 

 Portuguese (juinea is on tlie other hand rather narrower and smaller than tlie 

 Natal specimens, and the black colour on the wing-cases is rather differently 

 arranged, the yellow lines on the basal portion being more obliterated, while across 

 the middle the dark colour is more deficient, while it is again more predominant 

 before the extremity, so that it has a tendency to be divided into two patches 

 b_y an interrujition behind the middle. 



Africa and Arabia. (Natal, Lake Nyassa, Portugnese Ouinea ; Hedjaz;. 1022. 



JU25. Hydaticus decorus, Klug, M.C. — Uvalis, sat latus, nitidus, rufo-testaceus, 

 vertice prcthoracc basi in medio elytrisque nigris, his margine externo anguste, signa- 



