144 NATURAL HISTORY OP 



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- 



