Page:The Fauna of British India, including Ceylon and Burma (Butterflies Vol 1).djvu/10

vi entire absence of jugum or frenulum, though their substitute, the enlarged humeral angle to the hind wing, is always present; (2) by the knobbed, or dilated, or hooked antennæ. In certain families of the other main groups of the Lepidoptera, the jugum and frenulum are also absent; but then the antennæ are not knobbed, while in the families in which the antennæ are gradually thickened into a club, or are hooked like the antennæ of the Skippers, a frenulum is always present.

This work is primarily intended for collectors, and as an aid to the identification of Indian butterflies; no account, therefore, of the internal anatomy of the insects, in any stage, seems necessary, for little or no use has been made of internal differences for purposes of classification.

All Lepidopterous insects undergo a great and, to all appearance, an abrupt metamorphosis. In their life-cycle there are four stages:—

(1) The egg, which is round or oval, sometimes elongate, often flattened, and very frequently beautifully sculptured on the outside.

(2) The larva or caterpillar (fig. 1, I.), generally cylindrical, with or without a clothing of hair, often provided with protective tubercles, spines, or special fleshy filamentous processes. It is composed of a head and thirteen segments. Of the latter the first three are thoracic and bear pairs of jointed legs, the succeeding one or two simple without appendages, and one or more of the rest have fleshy feet or “prolegs” in pairs; the posterior pair, slightly different from the rest, are called claspers.

Fig. 1.—Larva (Vanessa). 1, head; 2-4, thoracic segments; 5-14, abdominal segments; a, true leg; b, proleg.

(3) The pupa or chrysalis (fig. 1, II.), more or less fusiform in shape, appendages cemented to the body by a corneous outer covering, often studded with tubercles or spines, or with strangely-formed, sometimes wing-like projections.

(4) The imago or perfect insect. Among the Papilionina, four