THE BUTTERFLY: STRUCTURE OF THE ARDOMEN. 45 



otliersthe pedicel i.s lialf as \o\v^ as tlie claws and the pad a lonrr incnil)ra- 

 nousflap, attached to it by one extremity ; the pad may take on almost any 

 form, hut is usually strongly apprcssed. Besides these terminal api)endages* 

 one or two pairs of hnig curving hairs, originating just above the base of 

 the claws, arch over and extend far beyond them ; this is especially notice- 

 able in the Ilcspcridac. 



The abdomen and its appendages. The abdomen of butterflies is 

 formed of nine segments, the tenth segment of the caterpillar having been 

 dropjH'd \\ ith the cremaster of the chrysalis. In general these segments 

 are very similar, but the first is always smaller than the succeeding (as in 

 the chrvsalis) and the terminal segments have si)ecial modifications accord- 

 ing to the sex. Excepting these terminal segments they have no appen- 

 dages and differ from the same parts in the earlier stages, in that the ui)per 

 and lower })lates of which each somite is made are corneous and distinctly 

 separated by a more or less membranous pleural interspace, within which 

 are situated the spiracles, on the first to the seventh segments only, the 

 spiracle of the eighth segment of the caterpillar having been dropped on 

 the assumption of the pupal condition. f Tiie al)domen is usually com- 

 pressed to a slight degree, sometimes considerably, and is always as long 

 as, o^enerallv lono-er, sometimes much longer than, the rest of thebodv, and 

 tapers at both ends. 



The posterior portion of the seventh segment of the female is modified 

 l)cneath to form, in conjunction with the anterior part of the eighth seg- 

 ment, a more or less wide-mouthed vestibule into the upper part of which 

 the vagina opens. The eighth segment in the same sex is much smaller 

 than the preceding, while the ninth is very small and forms merely a com- 

 pressed pair of short lappets serving as an ovipositor, being internally 

 grooved for the oviduct, and having immediately above that the anal open- 

 ing. 



In the male the seventh segment undergoes no modification, and ordi- 

 narily the eighth segment also assumes no special form, but in certain 

 instances it departs from this general rule. Thus, as Burgess first pointed 

 out, the sternal portion of the segment is enormously produced in Eu- 

 ploeinae to form lamellate lappets, which simulate the lateral appendages 

 characteristic of the succeedino- segment in butterflies, and so are termed 

 by him "false claspers" ; so also, the median part of the notal piece of the 

 same segment in Pierinac, as the same observer noted, is produced poste- 



* A dirtercnt account of those appeiulayos is iiig. If tlic erucifonii condition of the young 



given by Burmeisler (Lep. Rep. Arg.,1S-l!)). ))e regarded, as niorpliologists now consider 



t This is correllated with and undoul)tedly it, as an acquired characteristic, the spiracle 



conscfiuent upon the needs of this segment in of the eighth alidonunal segment must he 



the female hutterfly, the segment being here looked on as of late origination, and its fre- 



]irofoundIy modified l)oth externally and in- quent lack of alignement with the others and 



ternally by the necessities of the vaginal open- greater size may be more readily explained. 



