INTRODUCTION. H 



P. memnon, some of which have a large spatulate tail to the hindvving, while in others no sign 

 of a tail is visible. The wings consist of a fine translucent membrane, permeated by a number 

 of ribs, like the veins of a leaf or the rays of a fish's tin, and the whole covered more ur less 

 densely, both above and beneath, with tiny scales in which the colours of the wing lie. These 

 ribs have been styled by various authors as " nervures" and " nervules," or " veins " and 

 "venlets," or "rays." In this book the former terms are adopted, the nervures signifying the 

 main ribs, and the ttervules, the branches which they throw off. In describing the wing of a 

 Butterfly (see PI. I.), the junction of the wing with the body is called the base (A); the 

 margin nearest the heai' from the base outwards is caWcd i\\Q costal margiit, ox costa, ox the 

 antci-ior margin (A B) ; at the end of the costal margin, furthest from the body, is the apex (B); 

 the margin furthest from the head from the base outwards is called the inner or interior margin 

 (A C), and in the hindwing \\\t abdominal margin (A D) ; at the end of the inner margin 

 furthest from the body is the hinder ox posterior angle (C), and in the hindwing the anal angle 

 (D) ; and, lastly, the margin between the apex and the hinder angle is called in this book the 

 outer or exterior margin (A C and C D) ; this latter margin has been termed also by some authors 

 the apical margin. Ihe term hinder (or posterior) margin has been used by authors with 

 refeience both to the outer and inner margins. In accordance with these terms the 

 adjacent parts of the wing are referred to severally as the basal or sub-basal, costal or sub- 

 costal, apical or sub-apical, anal or sub-anal, &c. — the prefix "sub" being used to denote 

 " near to," as basal, at the base — sub-basal, near the base. When the margin alone is men- 

 tioned, as in describing marginal lines or rows of spots, the outer margin alone is signified. The 

 wings are said to be entire when the margin is not serrated or incised in any way. 



The neuration, or arrangement of the nervures and nervules, follows the same general plan 

 in all Butterflies, though the diversities in detail are numerous and of great value in discriminat- 

 ing fomilies and genera (see PI. I.) ; the costal net vure {a) starts from the base nearest the head 

 and extends just below the costal margin, ending in that margin usually at some distance shoit 

 of the apex. The costal nervure of the forewing is always simple, but in some of the 

 MorphincB it appears to throw off one or more branches towards the costal margin ; in the hind- 

 wing there is also usually a small nervure zz}i\Qi\^\t piecostal nervnre (.j'), close to the base 

 and between the costal nervure and the costal margin, it is short, recurved and 

 sometimes bifid ; immediately below the costal nervure is found the subcostal nervure 

 (b). which is continued to the outer margin a little below the apex ; this nervure throws off two 

 branches or nervules in the hindwing and three, four or five in the forewing (bi, b2, b^). 

 All the branches of this nervure are invariably thrown off on the upper side towards the 

 costa, and either end in the margin near the apex, or coalesce with the costal nervure. They are 

 numbered in order aS thrown off from the base— that nearest the base being the first subcostal 

 nerz'iik, the next the second, and so on. \vi\\\e. ElymniincE Tva^ some others there is a short 

 slender nervule connecting the subcostal with the costal nervure near the base; the space 

 thus enclosed is called ihe prcediscoidal cell. Below the subcostal nervure is a wide space (/;) 

 owing to the discoidal nervure which should follow, being either wholly or partially wanting. 

 This space, which is usually closed by short transverse nervules, is called the cell ox discoidal 

 cell; the short transverse nervules (g g) closing the cell are termed the disco-cellular nervules, 

 and are three in number (upper, middle, and lower) in the forewing, and two in number (upper 

 and lower) in the hindwing, the "upper" being the one nearest to the subcostal nervure. 

 From the points of junction of these disco-cellular nervules with each other, the discoidal 

 ver-vides (ci, c2\ two in the forewing and one in the hindwing, extend to the outer margin, 

 these discoidal nervules being considered as branches of a discoidal nervure, which, as noted 

 above, is either partially or wholly wanting ; the discoidal cell on its lower edge is bounded 

 by a strong nervure ('/), termed the median nervni-e. This nervure has three branches, both in 

 the fore and hind wings (r/r, di, d-^, called the W('(//Vi// M^7t'/</^j-, which in this case are all 

 invariably thrown off on the underside towards the outer margin, and being numbered in 

 order as they are thrown ofT from the base, they reach the outer margin in inverse order, the 

 first ending nearest the hinder angle, and the third nearest the apex. The lower disco-cellular 

 nervule (when present) closes the cell by junction with the median nervure ; below the median 



