234 LEPIDOPTERA. 



and the femora, tibiae and tarsi, slender and very equal in 

 length. There are usually two tibial spurs. The tarsus is 

 five-jointed, the terminal joint ending in two slender claws. 



The scales covering the body of Lepidoptera are simply 

 modified hairs. In studying the wing of the Cecropia moth, 

 we find the hairs of the body and base of the wing gradually 

 passing into the forms represented in Fig. 16G. They are 

 attached to the wings and laid partially over one another like 

 the tiles on a roof (Fig. 167). They are inserted in somewhat 

 regular lines, though, as seen in the figure, these lines are often 

 irregular, as shown by the line of scars where the scales have 

 been removed. The scales are beautifully ornamented with mi- 

 croscopic lines. We find, on removing the scales, that the 

 head consists of three well-marked pieces,* i. e. the occiput 

 or basal piece which lies behind the ocelli ; the epicranium, 

 lying behind the insertion of the antennae, and earning the eyes 

 and ocelli, and the clypeus, which constitutes the front of the 

 head. The latter piece is larger than in all other insects, its 

 size being distinctive of the Lepidoptera. There is a general 

 form of this piece for each family, and it affords excellent 

 characters in the diiferent genera, especially among the butter- 

 flies (as Mr. L. Trouvelot has shown us in a series of drawings 

 made by him), and the Zygwnidce and Bombycidce. It is 

 largest, and most perfectly shield-shaped, in the Attaci. In the 

 Phalcenidce, it is smaller, and square; and in the Tine idee 

 it is smaller still, while the occiput and epicranium are 

 larger. 



The labrum is remarkably small and often concealed by the 

 overhanging clypeus. The labium is small, short, triangular, 

 and the mentum is nearly obsolete. The lingua is obsolete, its 

 place being supplied by the tongue-like maxillae. The labial 

 palpi are feebly developed, sometimes rudimentary, and consist 



*FiG. 168. A, head of Ctenucha Virginica denuded; oc, occiput; ec, epicranium, 

 with the two ocelli, o, and the base of the antenna;, at ; e, eye; c, clypeus; I, la- 

 brum; m, mandible: mx, tongue, or maxilla?, with the end split apart; B, rudimen- 

 tary maxilla of Actias Luna, with its single-jointed rudimentary palpus, showing 

 the mode of attachment to the base of the maxilla; C, two-jointed, rudimentary 

 labial palpus of A. Luna; D, the same, single jointed, of Platysamia Cecropia. 



FIGS. 169, 170. Head of amoth in relation to the prothorax (1). FIG. 171, A, B, side 

 view and (C) front view of the head of a moth ; a, antenna ; b, eye ; rf, the " front ; " 

 e, orbit of the eye; /, ocellus; g, maxilla situated between h, the three-jointed la- 

 bial palpi ; i, the maxillary palpus, sometimes very large and three-jointed. 



