22 COLEOPTERA. 



FAMILY I. Dytiscidce. 



Antennae filiform, rather long ; palpi short ; eyes not divided ; 

 front pair of legs not longer than the hinder pairs, which are 

 fringed with hairs. 



Haliplus Fulvus, Fabr., is a reddish beetle about an eighth of 

 an inch long, with dusky streaks on the elytra. The species of 

 Haliplus, Latr., and Gnemidotus, 111., are found in stagnant water, 

 and differ from the other Dytiscidce in the antennae being only ten- 

 jointed, instead of eleven- jointed. 



The most extensive genus of the Dytiscidce is Hydroporus, 

 Clairv., which includes a great variety of small species, found in all 

 parts of the world, but especially numerous in Europe. They are 

 generally black, reddish, or yellowish, and more or less convex. 

 In this and some allied genera the front tarsi of the males are 

 only four-jointed. 



Colymbetes, Clairv., includes larger species, measuring half an 

 inch or more in length. One of the commonest species is C. Fuscus, 

 Linn., a brown oval beetle, with the sides of the collar and of the 

 elytra tawny. In this and several allied genera the front tarsi 

 are dilated in the males. 



The genus Agabus, Leach, includes a considerable number of 

 species about a quarter of an inch long, some of which are remark- 

 able for the antennae being dilated and serrated at the extremity 

 in the males. The type of the genus is A. Serricornis, Payk. 



Hyphydrus Ovatus, Linn., a species rather less than a quarter of 

 an inch long, is remarkable for its shape, being much shorter and 

 broader than most of its allies, and very convex ; it is of a reddish- 

 brown colour, and is found in stagnant water. 



The largest species of the Dytiscidce belong to the genus Dytiscus, 

 Linn., and measure from an inch to an inch and a half in length. 

 The tarsi of the males are dilated, and the elytra of the females are 

 strongly furrowed. They are of an olive brown or dull greenish 

 colour, with yellowish borders to the thorax and elytra. They are 

 broad insects, hardly convex ; and D. Latissimus, Linn., one of the 

 largest, but by no means one of the commonest species, is nearly 

 as broad as it is long. The larvae of these insects are sometimes 

 called " Fresh-water Shrimps." Both the beetles and their larvae 

 are very voracious, and the former will even attack and devour 

 small fish. They are more often found in standing water than in 

 streams. 



