﻿66 BUITISH BEETLES. 



2. The GYRINID.E differ vastly in structure from 

 all the above. They have four eyes ; two on each side, 

 one above and one below (Plate III, Fig. 6*) ; the ordi- 

 nary single eye being divided by the cup formed for the 

 articulation of the antennse : the palpiform outer lobe of 

 their maxillae is wanting, except in the genus Gyrinus, 

 where it is extremely small, slender, and rudimentary ; 

 their antennse are short, robust, and stiff, the second 

 joint being very large and ear-like, with the third and 

 remaining joints jammed together and inserted in its 

 middle (Plate III, Fig. 6''). The anterior legs are long 

 and slender, and the intermediate and hinder pair close 

 together, removed from the front, and extremely com- 

 pressed, with the femora, tibiae, and basal joint of the 

 tarsi very broad and triangular (Plate III, Fig. 6'"). The 

 Gyrini, commonly known as " water-fleas," " whirlwigs," 

 or " whirligigs," may be seen in fine weather forming end- 

 less " figures of 8 " on the surface of both running and 

 still waters. Tiiey are small, metallic, shiniug black, 

 elongate beetles, exceedingly wary and quick in their 

 movements, and with a power of exuding a very nasty- 

 smelling acrid milky fluid, from nearly all parts of the 

 body apparently, when handled. This fluid is analogous 

 to that secreted by some Geodephaga, which it resembles 

 in evil odour. The female lays small cylindrical eggs, 

 end to end, in level rows, on water-plants, the larvse 

 proceeding from which are very peculiar, being narrow 

 and flattened, with a long slender filament rising out of 

 each side of all the segments except those bearing the 

 legs. These filaments act as air-conductors, and give 

 the animal the look of a Centipede. When full-grown, 

 it ascends water-plants, and forms a small oval cocoon, 

 of a substance like grey paper, in which it assumes the 

 pupa state. 



