COLEOPTEROUS INSECTS. 
139 
Throughout the greater part of the year there is 
scarcely a sheltered pool without a group of these 
agile little creatures, pursuing their avocations with 
the most sportive alacrity. Their chief occupation 
is swimming rapidly along the surface in concentric 
circles, or darting about in irregular gyrations, an 
exercise which they keep up during the whole day, 
without any apparent object but the love of motion. 
Their bodies are so highly polished, that they shine 
like a piece of burnished metal, and not a particle 
of water can adhere to them. When approached 
or otherwise interrupted, they speedily scatter or 
dive under the water, but soon re-appear and resume 
their sports. Their circular movements are no doubt 
produced by the natatory legs on the one side being 
more rapidly moved than on the other, as a boat is 
turned when the rowers on one side cease to ply. 
In collecting into parties, and leading up their mazy 
dance together in the sunshine, we may suppose 
these little creatures to be actuated by the same 
social feeling which Mr Wordsworth has ascribed 
to the gnat-like flies ( Tipulida ), which assemble in 
choirs, and may be seen in sheltered situations 
even in the middle of winter, alternately rising and 
falling with a rapid undulatory motion. 
Nor wanting here to entertain the thought, 
Creatures that in communities exist, 
Less, as might seem, for general guardianship, 
Or through dependence upon mutual aid, 
Than by participation of delight, 
