COLKOPTERA. ' — GYRINIDiE. ] 09 



its different states. The larva {^fig. 6. 18.) is long, narrow, and do- 

 pressed, and nearly resembles a small centipede, of a dirty white co- 

 lour, composed of thirteen segments (including the head), separated 

 from each other by lateral incisions ; the head is large, oval, and de- 

 pressed, armed with two strong jaws, two short filiform 4-jointed an- 

 tennae, several small tubercular eyes (the number of which De Geer 

 could not discover), forming a group on each side the head, and slender 

 maxillary and labial palpi ; the clypeus is deeply notched in front, 

 without any distinctly articulated labrum; to each of the three ante- 

 rior segments of the body is attached a pair of moderately long and 

 slender legs ; and from each side of each of the eight following seg- 

 ments arises a long, slender, transparent, and membraneous filament, 

 bent rather backwards, and terminating in a point ; the terminal seg- 

 ment is furnished with two pair of similar but much longer appen- 

 dages. These filaments are employed as organs of respiration, each 

 being internally provided with a delicate air-vessel, connected at the 

 base with the ordinary lateral tracheae ; the body is terminated by 

 four minute conical points, bent downwards, and which are used by 

 the insect when in motion ; whereas the long filaments have no pe- 

 culiar motion. When the larva has attained its full size, at the be- 

 ginning of August it creeps out of the water, up the stems of the 

 rushes, or other aquatic plants, where it encloses itself in an oval co- 

 coon, pointed at each end, composed of a substance spun out of its 

 own body, and somewhat resembling grey paper, within which it be- 

 comes a pupa, in which state it remains about a month, when it makes 

 its appearance in the perfect state, and immediately resorts to its native 

 element, the neighbouring water. Mr. R. Patterson of Belfast, has 

 communicated to me the discovery of a specimen of Orectochilus vil- 

 losus inclosed in a fresh-water shell taken out of a pool, the mouth 

 of which was stopped with a piece of some plant, with slime, and 

 which was lined with a soft, whitish, silky substance, extending to the 

 margin of the aperture. It was supposed that the larva had taken 

 possession of the empty shell, in which to undergo its transformations. 

 (See also Ent. Mag., ii. p. 530.) Mr. H. W. Griesbach has, however, 

 discovered the whitish silky cocoons of this species beneath the bark 

 of a rotten willow tree, at a yard's distance from the edge of a river, 

 and about two feet from the ground. {Ent. Mag. iv. p. 254.) 



The Gyrinidae were at first united by I-inn;tus with the Dyticida?; 

 but this author subsequently adopted the genus Gyrinus, as proposed 



