658 On Aquatic Carnivorous Coleoptera or Dytiscide. 
This peculiar species has the colour of a Dineutes a genus of Gyrinidee, 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 distinguish 
it from the species of Hydaticus, although it has the epipleurz 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 
sculpture, 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 Marquis J. Doria in 1865-66, Genoa Mus.) 1023. 
1024. Hydaticus flavolineatus, Boh., M.C.—Major, robustus, ovalis, subtus 
ferrugineus 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 testacels 1n 
lineas longitudinales nigras diviso, lineis his nigris preesertim 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 the 
palettes are large those at the base bemg specially large. The 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 shows no trace 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 are broader, and the black colour on the 
elytra has more obliterated the yellow lines on the apical portions of the elytra, 
and the female has no peculiar sculpture on the thorax. The individual from 
Portuguese Guinea is on the other hand rather narrower and smaller than the 
Natal specimens, and the black colour on the wing-cases is rather difterently 
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 
by an interruption behind the middle. 
Africa and Arabia. (Natal, Lake Nyassa, Portuguese Guinea ; Hedjaz). 1022. 
1025. Hydaticus decorus, Klug, M.C.—Ovalis, sat latus, nitidus, rufo-testaceus, 
vertice prothorace basi in medio elytrisque nigris, his margine externo anguste, signa- 
