256 BRITISH BUTTERFLIES. 



protected by an extensive posterior expansion of the terminal segment 

 of the abdomen, which forms a projecting hood, and which is also 

 provided at the tip with a heavy fringe of excessively long scales ; the 

 clasps are themselves furnished externally with a heavy coating of 

 pretty long scales, which effectually hides the sculpture of the parts, 

 although the disparity in length of the two clasps is readily seen («.//., 

 Thanaos brizo). Scudder further states that, when a $ of one of these 

 species is taken between the fingers, the insect frequently endeavours 

 to use this apparatus as an organ of defence, or, perhaps it might be 

 said, of aggression, much after the manner of a Panorpa or a Staphy- 

 linus. Of the structure of the genital organs, Scudder writes : 



" The 8th abdominal segment is broadly produced aboA*e in the $ , in a convex, 

 entire, rounded plate, the whole fully three times as long as the preceding segment, 

 and furnished with very long scales ; the side-pieces (clasps) of the d are fringed with 

 numerous, not very long, hairs, and covered profusely with short scales, and are 

 long and slender, directed a little upward, and apically inward. The upper organ 

 varies exceedingly in shape and proj3ortionate size ; the centrum gibbous, subovoid, 

 contracted towards the tip, and bearing, at the extremity, a pair of hooks, occasion- 

 ally consolidated, and from the inferior junction of which, a minute, appressed, central 

 plate or tooth, dentiform on a side view, frequently depends ; near the middle of the 

 upper portion of the centrum, the surface is either simply a little elevated, or 

 expanded, after elevation, into nearly horizontal alations, or it rises into a dorsal, 

 usually horseshoe-shaped, crest, the sides of which sometimes form conspicuous 

 lateral expansions, the whole crest being frequently asymmetrical in elevation and 

 lateral extension, and bearing, on its upper edge, an armature of spines ; from the 

 middle of the ujoper surface, lateral arms extend downward, and then curve back- 

 ward, meeting behind, and, at their united extremities, expand into a transverse, 

 usually broad, field, the inferior armature well provided with spines or bristles. 

 Besides the asymmetry of the dorsal crest referred to, the lateral arms, the terminal 

 hooks, and the inferior armature, frequently partake of the same peculiarity ; indeed, 

 this element seems to pervade every part of the remarkable genital armature in this 

 genus. With some minor exceptions, the left clasp is always more highly developed 

 than the right, both in the configuration of the whole, and in the sculpture and 

 armature of the details ; each clasp may be divided for convenience of description, 

 into two parts — an upper and a lower ; the upper portion is ordinarily developed as 

 a broad lobe, armed on its upper edge with a row of very long, stiff bristles, pointing 

 backward ; it has a tendency to expand in two directions, forming what are called the 

 upper and hind processes, according to their position ; the lobe is generally smaller 

 in the left clasp than in the right ; and the hind process either wanting, or minute, in 

 the left. The lower part of the clasp is a very long, slender, usually compressed, 

 often twisted, and invariably curving, blade, frequently spined or pointed at tip, its 

 origin marked below by a denticle ; it bears, at the base of the upper edge, a short, 

 frequently bent or curving process, ordinarily somewhat triangular in shape, and 

 very often armed with spinules ; sometimes this process is wanting on the right 

 clasp, and it is usually more slender, and frequently longer, on the left than on the 

 opposite side ; at their base, the clasps form a large, broad, compressed, somewhat 

 gibbous plate, of variable form." 



The movement of the clasps is, of course, lateral, and that 

 of the upper organ, vertical ; but some of the constituent parts of 

 the latter have an independent motion, the whole central apparatus, 

 including the hooks, having a common vertical movement upon 

 the centrum, and the central tooth a forward and backward swing 

 upon the apical portion. 



Closely allied species vary in the amount of development of the costal 

 fold and its enclosed androconia. These latterwere described at length by 

 Aurivillius (Bid. Sums. Vet.Akad. Handlingar t y,,ip. 32), and Scudder ob- 

 serves that an examination of the androconia has shown, so far as these 

 scales are concerned, bow colsely some of the species are related to each other, 



