BASIS OF CLASSIFICATION. 
9 
only to a partial transformation. The parts of the legs are the 
hip-joint, by which the leg is fastened to the body, the thio-h, 
the shank ( tibia ), and the toot, the latter consisting some- 
times of one joint only, more often of two, three, four, or five 
pieces (tarsi'), connected end to end, like the joints of the 
finger, and armed at the extremity with one or two claws. 
Ot the larvae that undergo a complete transformation, mag- 
gots and some others are destitute of legs ; many grubs have 
six, namely, a pair beneath the under-side of the first three 
segments, and sometimes an additional fleshy prop-leg under 
the hindmost extremity; caterpillars and false caterpillars 
have, besides the six true legs attached to the first three 
rings, several fleshy prop-like legs, amounting sometimes to 
ten or sixteen in number, placed in pairs beneath the other 
segments. 
The abdomen, or hindmost, and, as to size, the principal 
part of the body, contains the organs of digestion, and other 
internal parts, and to it also belong the piercer and the sting 
with which many winged or adult insects are provided. The 
piercer is sometimes only a flexible or a jointed tube, capable 
of being thrust out of the end of the body, and is used for 
conducting the eggs into the crevices or holes where they are 
to be laid. In some other insects it consists of a kind of scab- 
bard, containing a central borer, or instruments like saws, de- 
signed for making holes wherein the eggs are to be inserted. 
The sting, in like manner, consists of a sheath enclosing a 
sharp instrument for inflicting wounds, connected wherewith 
in the inside of the body is a bag of venom or poison. Tbe 
parts belonging to the abdomen of larvae are various, but are 
mostly designed to aid them in their motions, or to provide 
for their respiration. 
An English entomologist has stated, that, on an average, 
there are six distinct insects to one plant. This proportion 
is probably too great for our country, where vast tracts are 
covered with forests, and the other original vegetable races 
still hold possession of the soil. There are above 1,200 
2 
