690 On Aquatic Carnivorous Coleoptera or Dytiscide. 
1081. Sandracottus nauticus, n. sp.—Ovalis, sat latus et convexus, nitidus, niger, 
capite elytrisque nigro testaceoque variegatis, thorace ad latera testaceo ; elytrorum 
signaturis testaceis haud magnis. Long. 144, lat. 82 m.m. 
In this species there are three series of black marks on the head, the vertex 
being black, and in front of it two large black marks, not quite connected to one 
another, bat confluent with the black at the inner margin of the eye, while in front 
of these two marks there is another angular dark mark. The thorax is black with 
the sides yellow. The elytra are black with yellow marks transversely disposed on 
them, viz., three basal small spots, an elongate but narrow humeral mark emitting 
behind a prolongation towards the middle, two marks just behind the middle placed 
so as to form an interrupted transverse band, a subapical oblique mark, and a 
minute apical spot ; the yellow colour of the humeral mark is prolonged backwards 
along the outer margin to just beyond the post-medial mark, but becomes towards 
its termination a little separated from the margin. 
I have seen only one individual of this form, and a variety in which thé yellow 
spots on the elytra are greatly reduced in size: it is considerably smaller than 
Hydaticus maculatus, Wehncke, and rather different in form, being not so narrow 
in front, and the yellow colour along the margin of the elytra is much less prolonged 
in the posterior direction. 
Borneo. 987. 
1082. Hydaticus maculatus, Wehncke, Stet. Ent. Zeit. XXXVII, p. 196.— 
Major, ovalis, latiusculus, anterius angustatus, parum convexus, subtus piceus, 
supra niger, capite elytrisque nigro testaceoque variegatis, thorace ad latera 
testaceo ; elytrorum signaturis testaceis haud magnis. Long 153, lat. 8? m.m. 
The front of the head is yellow, the vertex is largely black, on the middle are two 
large black marks, which are connected, and so extended as to reduce the yellow 
colour between them and the vertex to a transverse line, or even in extreme cases 
to two small spots ; there is a vaguely defined dark angular mark in front of these 
marks, on each wing-case there are three small basal spots and an elongate humeral 
mark yellow, this latter giving off near its extremity a prolongation inwards ; just 
beyond the middle there are variable yellow spots, sometimes forming an irregular 
cransverse band, there is also a small, subapical, oblique mark, and a quite minute 
spot at the tip yellow: the yellow colour of the humeral mark extends backwards 
along the outer margin as far as the cblique subapical mark. The spots of yellow 
colour are very variable, never extensive, they are sometimes reduced to a few 
small specks ; the yellow marginal colour is however apparently subject to little or 
no variation in its extent. The female seems to be rather larger than the male. 
The Malay peninsula. 988. 
