82 
INSECTS. 
Heterocera implies, furnish us with far greater variety in the form of the antennae; 
quite apart from the fact that they differ in both sexes of the same species, thread¬ 
like, for instance, in the female, pectinate in the male sex, we find at least ten 
different forms of antennae amongst members of this section •.—Filiform, or thread¬ 
like, gradually tapering to a point; fusiform, broadened from the base onwards 
to the tip, which is again narrowed; dilate, narrow from the base to about one- 
third its length, then rather suddenly enlarged, and again narrowed at the tip; 
ciliate, clothed with the finest hairs; setigerous, each joint furnished with a bristle 
on either side; setigerous and ciliate, furnished with both fine hairs and paired 
bristles; fasciculate, each joint furnished with a group or tuft of short bristles, 
like a small brush; dentate, or toothed, each joint produced into a sharp tooth-like 
process at the side; lamellate, where each joint is produced at the margin into a 
small plate-like prominence; serrate, sawlike, each joint produced into a short 
sharp point at the side, giving the whole antennae the appearance of a saw, the 
teeth are not so long as in the dentate antennas; 'pectinate, each joint furnished 
with long plume-like hairs, or a pair of such on either side. 
Thorax and its The second division of the body, like that of the Hymenoptera, 
Appendages. j s composed of three closely united rings, each bearing beneath a 
pair of legs, while the posterior pair carry also on their upper or outer sides, each a 
pair of well developed wings. The prothorax bears the 
fore-legs. The mesothorax the mid-legs and fore-wings. 
The metathorax the hind-legs and hind-wings. The 
legs are not used normally for walking, but are chiefly 
serviceable for clinging to objects while settling or at 
rest. They do not call for any special mention; and 
are not of great account for purposes of 'classification, 
except in the butterflies, where in the case of the males 
of the three families Nymphalidce, Erycinidce, and 
Lyccenidce, the fore-pair are much reduced in size, 
being in some cases almost rudimentary. 
By far the most important structure in the eyes of 
the general naturalist, though not necessarily so in 
the opinion of the expert, are the beautiful membranous, scale-clad pinions. 
These give the distinctive character to lepidopterous insects, and render them so 
fascinating to the lover of nature. Broad and ample on the whole amongst the 
butterflies, more narrowed as a rule amongst the moths—the hawk-moths for instance 
—they are formed of the finest transparent membrane stretched out between the stiff 
rib-like nervures, or, more properly speaking, veins, which carry the nutritive fluids 
from the central system to all parts of the structure. The nerves, as custom will 
persist in terming them, in the butterflies take a bow-like or ellipsoidal sweep from 
the base of the wing, forming what is called the discoidal cell, whence there branch 
off to the edges a series of horizontal, almost parallel, slightly divergent, nervures. 
On the position of these the identification of species is most securely based, though, 
in order to examine them, the insect must be spoiled as a specimen. In the moths, 
on the other hand, the discoidal cell is less conspicuous, though nervures branch off 
divergently from the base of the wing in a somewhat similar manner to those of 
LEFT FORE-WING OF A NOCTUA 
MOTH. 
a, b, c, h, indicate the normal 
position of the transverse 
bands, a, costal margin ; f, 
inner margin; d, discoidal 
spot; e, reniform spot. 
