1 44 NATURAL HISTORY OF 
be distinguished by the name of Palpicornes. The 
antennae usually consist of nine joints, which become 
larger towards the upper extremity, and are con- 
nected by a filament, which has the appearance of 
passing through them. The genus most deserving 
of notice, is that first established by Dr Leach under 
the name of Hydrous. It is known by having the 
labrum entire, the posterior claws bifid, the elytra 
narrowing gradually behind, and the great size of 
the teeth on the internal edge of the mandibles. 
HYDROUS PICEUS. 
PLATE IV. Fig. 4. 
Dytiscus piceus, Linn. — Hydrophilus piceus, Fab — Hyd. 
piceus, Curtis ’ Brit. Ent. v. pi. 239 ( from which the ac» 
companying figure is taken). 
The ground colour is black, inclining to olive, 
and the margins of the elytra are faintly tinged with 
green and purple. The antennae and organs of the 
mouth are reddish. Each wing-case is marked with 
eight dotted lines, and the alternate interstices with 
an irregular series of dots. The breast is clothed with 
yellowish hair, and there are several yellow spots on 
each side of the abdomen. The legs are of a pitchy 
colour, with the extremity of the tarsi, and the hairs 
with which they are fringed, reddish brown. 
This is the largest aquatic beetle inhabiting Bri- 
tain, and, indeed, with the exception of the Stag- 
