The ninth somite in the male is inclosed by the eighth. It consists of two narrow lateral chitinous bands which meet with expanded ends dorsally and ven-trally. Each band consists of a median, a dorsal and a ventral piece, the whole forming an S-shaped figure. Strong muscles are attached to these pieces. The valves which inclose the male genital organ and the anal papilla are attached to the posterior edges of the ventral pieces. Each valve is trigonal, concave internally, its margins fringed with long hairs. Near the ventral edge of its inner surface is a curved chitinous lamella, feebly toothed, - the harpe of Gosse (?=harpagon of White). To the posterior edges of both dorsal pieces of this ninth somite is articulated a stout decurved pointed process terminating in two hooks, the uncus of Gosse or tegumen of White. It immediately overhangs the slender anal papilla. A band of chitin connected with the base of the uncus, and continuous from side to side, curves under the same papilla, and from its mid ventral-point project two slender rods which appear to correspond to the scaphium of Gosse. The penis projects from the cavity below, i. e. in front of these rods, and above, i. e. behind the ventral union of the pieces of the ninth somite.
The uncus appears to correspond to the cremaster of the pupa, the anal valve of the caterpillar. The bar curving below the anus may be either a chitinisation in the tenth or anal somite, or a dissociation from the ninth.
In the female the seventh somite is much elongated. Its sternum is small and triangular, its pleural membranes large and meeting posteriorly and ventrally. Somites eight, nine, and ten are inclosed by it. The eighth is short dorsally, long ventrally. It has a small pleural membrane. Its sternum is strongly chitinised, grooved ventrally, and the groove narrows anteriorly, serving as a guide to the large orifice of the bursa copulatrix. The ninth somite is soft in texture. A very narrow band represents its dorsal and lateral regions; its ventral region is thickened with a linear ventral groove. The tenth somite is represented by a large papilla slit vertically. Its sides are thickened, rough and pilose, and in the slit the anus opens above and the vagina below1.
1 De Lacaze Duthiers, in his series of classical papers on the genital armature of female Insecta, places the aperture of the bursa copulatrix of the Lepidoptera behind the sixth somite, instead of behind the seventh in the sternal region of the eighth, its ordinary position in Insecta (see the table on p. 230, A. Sc. N. (3) xv. 1853)., except in Ephemeridae, where it lies in the seventh intersegmental membrane. De Lacaze Duthiers does not recognise the altered first somite nor the exact position of the orifice of the bursa. Newport recognises the first somite, but has not described the differences between the male and female. His figures (Figs. 391, 392, pp. 922, 923, Article Insecta, cited below) are from a male. The correctness of the view taken above may be gathered partly from the account given of the pupa, partly from the relations of the spiracles (infra).
The structure of the body as above described is probably typical of the Lepidoptera, but the subject is one that calls for investigation. The region of the first abdominal somites seems the most variable.
The spiracles are vertical slits as in the previous stages. The last abdominal spiracle, the eighth, is aborted. A slight scar indicating its position may sometimes be found in the male. The remaining spiracles are the prothoracic and seven abdominal. The former is situated in the soft skin between the pro- and meso-thorax, nearer to the prothorax. The first abdominal is the largest of the whole series. It lies in the pleural membrane under the edge of the lateral piece of the first tergum, i. e. on the abdominal side of the thoraco-abdominal constriction1. The other spiracles are all situated in the pleural membranes of their respective somites. If the interior of the pupa skin is examined, the cuticle shed from the first portions of the tracheae may be found attached to all the pupal spiracles, with the exception of the eighth abdominal, thereby shown to be closed.
As to the mouth parts there is a labrum forming a narrow band with a median process and a lobe covered with hairs at each outer angle2. Mandibles are absent as articulated pieces, a characteristic feature, according to Walter, of all the Lepidoptera save Micro-lepidoptera (Tineinae, &c). But from investigations made upon caterpillars about to assume the pupal condition, it seems to me that two stout pointed projections of the genae, lying to the outer side of the lateral lobes of the labrum, are non-articulated representatives of these appendages. At any rate, they are formed at the base of the caterpillar's mandible. The maxillae consist of a cardo and stipes, imperfectly separated and immoveably united to the head. The palps are one-jointed and bear a tuft of hairs. But the bulk of the maxillae, the antliae, consists of the greatly-developed galeae. Each galea is prolonged into a long band spirally coiled when at rest; convex on its outer, concave on its inner, face, thus forming a channel. The faces are strengthened by independent systems of chitinous spots or rings.