282 DIVISION III. ARTICULATED ANIMALS.—CLASS IV. INSECTA. 
The thorax is short and transverse; the elytra are obtuse or truncated at 
the posterior extremity; the two fore legs are slender, long, folded up, 
and held nearly at right angles with the body when shut up, and terminated 
by a very short, compressed tarsus, of which the under side is clothed with 
fine plush in the males. The four other feet are broad, very thin, like mem- 
brane, and the joints of the tarsi form small leaves. 
The insects, which are called Whirlwigs, or Whirligigs, from their peculiar 
motions, are, in general, of small or but moderate size. They are to be seen, 
from the first fine days of spring till the end of autumn, on the surface of quiet 
waters, and even upon that of the sea, often assembled in great numbers, 
and appearing like brilliant points. They swim or run about with extreme 
agility, curvetting in a circular or oblique, or indeed in every direction, 
whence their ordinary French name of Tourniquets, or their English name 
given above. Sometimes they remain stationary, without the slightest mo- 
tion; but no sooner are they approached than they escape by darting under 
the surface of the water, and swimming off with the greatest agility. The 
four hind legs are used as oars, and the fore ones for seizing the prey. Or- 
dinarily stationed upon the surface of the water, the upper side of the body 
is always dry ; and when they dart down, a bubble of air, like a silvery ball, 
remains attached to the hind part of the body. When seized, they discharge 
a milky fluid, which spreads over the body, and probably produces the dis- 
agreeable odor which they then emit, and which lasts a long time upon the 
fingers. Sometimes they remain at the bottom, holding upon plants, where 
also they possibly hide themselves through the winter. 
In the third family are found the following interesting genera: Buprestis, 
Lampyris, Ptinus, and Elater. 
The Buprestide are noted for their splendid colors, some of which have 
spots of gold on emerald ground, while others exhibit a variety of metallic 
colors. 
Lampyris. — The Lampyridw have the elytra weak and soft, like the 
insects of the preceding tribe. In their perfect state, they frequent flowers. 
Their larvw are carnivorous, attacking other insects or worms. It is to 
this group that the Lampyris noctiluca, or Glow-worm, which one sees 
shining during summer nights on grass and bushes, belongs. The Jumi- 
nous properties with which these insects are endowed have for their object 
to reveal their presence to the opposite sex; for the females alone pos- 
sess these properties. In the same way as sounds or odors exhaling from 
some insects attract the one towards the other sex, so with the Lampyris a 
phosphorescent light shows the females to the males. The seat of the 
phosphorescent substance varies according to the species. It exists gener- 
ally under the three last rings of the abdomen, and the light is produced by 
