8 



AFRICAN MIMETIC BUTTERFLIES 



remarkable power possessed by the male insect of finding the female. This power is developed 

 to a marvellous extent in certain moths [Bombycidae), and in these the male antennae 

 are of unusually elaborate formation. 



The mouth parts consist of a much reduced upper lip or labrum between the atrophied, 

 or in some moths, partially atrophied, mandibles. Beneath this the trunk or haustellum is 

 situated. This organ corresponds to the second pair of jaws or maxillae found in biting insects. 

 It forms a tube through which the insect absorbs its food, and consists of two separable 

 portions closely attached together. Beneath this the lower lip or labium carries the organs 

 known as the labial palpi. These are three- jointed and are of importance in classification. 



The thorax is the muscular centre of the body to which are attached the head, abdomen, 

 wings, and legs. It corresponds to the second, third, and fourth segments of the larva, and 

 these segments may be traced in the arrangement of the chitinous plates of which it is 

 formed. The three pairs of legs are attached respectively to these three segments, and 

 the wings to the second and third. Two small plates or scapulae are attached above the 

 junction of the anterior wings. 



The abdomen consists of nine segments, a rudimentary tenth segment being recognized 

 by some authors, and carries seven pairs of spiracles, the orifices of the tracheae or 

 breathing organs. 



The legs, which are of great importance in classification, consist of three portions, 

 the thigh or femur, the shank or tibia, and the foot or tarsus. The femur and tibia form 

 two joints only, but the tarsus is five- jointed, the last joint being provided with claws, 

 generally two in number. The front tibiae sometimes have a narrow appendage on the 

 inner side and sometimes a claw-like appendage at the extremity. The two hinder pairs of 

 tibiae are usually furnished with a pair of spines at the extremity, and in one family of 

 butterflies [Hesperidae] the hinder tibiae have a second pair of spurs. In many butterflies 

 the fore-legs are only imperfectly developed. 



The wings are formed of a thin transparent membrane which is strengthened by a 

 system of chitinous tubes called nervures and nervules. The front edge of the wing is named 

 the costa, the side opposite to that the inner-margin, and the edge which lies furthest from 

 the body is called the hind-margin. The angle formed by the costa and the hind-margin is 

 the apex, that formed by the hind-margin and the inner-margin the posterior angle in the 

 fore-wing, and the anal angle in the hind-wing. The point of attachment of the wing to the 

 thorax is called the base. 



One of the principal features used in classification is the neuration, or arrangement 

 of the nervures of the wings. These arise either from the base of the wing or from other 

 nervures, in which case they are called nervules or branches. 



Various methods of nomenclature have been proposed for these structures. That adopted 

 here will be found to conform to most of the published descriptions. Fig. i shows the neura- 

 tion of the wing of a butterfly of the genus Amauris, and is somewhat similar to that found 

 in the genus Danaida, from both of which genera come many butterflies which appear to 

 form models for mimicry by those of other groups. Fig. 2 represents the wings of a butterfly 

 of the genus Hypolimnas. In examining drawings of the wing neuration of butterflies such 

 as may be found in Messrs. Staudinger and Schatz's work on that subject, a great variety 

 in the exact arrangement of the nervures will be observed, and these structures form the 

 basis of the more minute classification. At the same time there is sufficient regularity of 

 main nervures to enable a general system of nomenclature to be adopted. The following 

 description applies equally to the two figures shown, 



