VI INTRODUCTION. 



entire absence of ajugum or frenulum*, though their substitute, 

 the enlarged humeral angle to the hind wing, is always present ; 

 (2) by the knobbed, or dilated, or hooked antennae. In certain 

 families of the other main groups of the Lepidoptera, the jugum 

 and frenulum are also absent ; but then the antennas are not 

 knobbed, while in the families in which the antennae are gradually 

 thickened into a club, or are hooked like the antennae 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 suc- 

 ceeding 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. 



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 



* Present, so far as known, in a single aberrant form. Eusehemon rafflesice 

 from Australia, belonging to the Hcsperiidcs. 



