The hydrous piceus is here represented of the natural size; the ground colour is black, with a shade of bronze, and the margins of the elytra are tinged with green and purple. Each wing case is marked with dotted lines, the breast is dingy yellow, and the antennæ and organs of the mouth dull red. The legs are black, and the hairs which fringe the tarsi reddish brown.
COLYMBETES.
Colymbetes, of several species, may be obtained in plenty from clear brooks in every part of the country. These are elegantly-formed and lively beetles; their elytra, legs, thorax, head, and breast of the same jet-black hue, and highly burnished, though, when immersed, the breast and abdomen glisten with an intensely metallic silvery lustre, owing to the film of atmospheric air which the beetle obtains from the surface, and which adheres to the hairy covering of the abdomen. This silvery species is here represented in its natural size. They are comparatively harmless, though I have just witnessed the demise of one that was attacked and eaten by his pretty kindred, the wing-cases and head only remaining to testify of his former individuality. This is a delicate beetle, that requires very pure water and a neat arrangement of aquatic plants, to give full effect to its beauty as a cabinet specimen, and, when carefully preserved, a jar of them forms a conspicuous and attractive object. I have several specimens of a smaller species in a very fine jar of confervoids; they are incessantly in motion, threading their way through the interstices of the delicate vegetation in a business-like way, that seems to say, "I'm on an important errand—have not a moment to lose, and, above all things, I must take care of the bubble of air that sticks to my tail."
Gyrinus Natator.—This is a member of an interesting and pretty family. Gyrinus takes its name from the tendency most of the beetles of the tribe have to move in circles, and this particular species exemplifies the habit of the tribe in a very striking manner. It is a very sociable beetle, always found in company with others of its kindred, forming little communities, which pass their time in whirling and spinning upon the surface of still pools, like congregations of dancing dervishes. They are as shy as they are nimble, and it requires some dexterity to net them, for they dive and scatter on the approach of a footstep; but if the observer remains quiet a few minutes by the water's edge, or on a plank or bridge above the pool, they soon resume their gambols under his eye, and in the sunshine appear like minute buttons of burnished metal rapidly revolving or darting to and fro upon the surface, and for a length of time, that proves them to be by no means subject to giddiness.
GYRINUS NATATOR.
The species of Gyrinus are not numerous in Britain, not more than eight being known to naturalists; but the paucity of species is compensated by the profuseness of the individuals, and of these natator is the most abundant. When placed under a lens, this beetle bears the form represented in the next page. The colour is blue-black, with a resplendent metallic lustre, in which shades of copper, silver, and bronze occur, as we view it at various angles to the rays of light. The thorax is marked with three transverse lines on each side, of which the anterior one is punctured, and runs parallel with the margin. The elytra are turned in at the sides, and the surface of each is marked with eleven striæ or longitudinal lines, composed of minute punctures. The terminal segment of the abdomen, together with the legs, are of a rust-red.
