IN CERTAIN LEPIDOPTEEA. 279 



wiry penis issues from a conical sheath, which closely envelops it, as if an organic part 

 of it. This does not appear to he a process from the scaphium. 



Finally there is that remarkable dividing wall, of hard, horny chitine, which I describe 

 and figure in Erithonius, perforated in the middle, manifestly for the egress of the penis, 

 yet which, strange to say, I have met with in no other species *. 



Tue Purpose of the Structural Variations. 



If it be asked, What i§ the definite purpose, in the economy of the creature, of this 

 extreme variation ? I am obliged to answer, I do not know. That, viewed in the large, 

 the object of all these organs that crowd around the termination of the male abdomen is 

 the firm grasp and sustained retention of the female abdomen, in the delicate and most 

 essentially important function of reproduction, is sufficiently evident. But why the 

 diversity of detail ? Why would not one good and adequate form suffice, again, and 

 again, and again, subject to no more variation than are the antenna?, for example, or 

 the tarsi ? 



It naturally occurred to me, very early in these researches, that every peculiarity in 

 the prehensile organs of the male would have a correspondent peculiarity in that 

 part of the female body which they were formed to grasp ; and I eagerly turned to the 

 examination of the female abdomen. But the repeated search left-, and still leaves, my 

 Question — cui bono ? — without an answer. 



The position of these organs, and their relation to the surrounding parts, when in situ, 

 show indubitably that it is the exterior of the final segments of the female abdomen, 

 that are seized in coitu. The harpes and the uncus are certainly not intruded into the 

 female abdominal cavity. Thus the field of search is at once limited to the outer surface, 

 nrom the very nature of things ; and this is confirmed by the occasional clogging of the 

 |iarpes with body-scales, as I have already noticed. It was then sufficient to denude the 

 female abdomen of its clothing-scales, without disturbing the parts. 



But though I did this with species after species, selecting those whose males have 

 Inversely-armed harpes, no solution of the inquiry was obtained. The females of Pa pit "to 

 \Thoas, Poli/damas, Anchisiades, Ileteuits, are, as to the point in question, mutually 



I * The genital organs unci their accessories have been minutely described and exquisitely figured in another Order of 

 cts. The question maybe asked,— What homology (or analogy ?) exists between the organs herein described 



me and those of Trichoptera described by Mr. McLaehlan? I have examined every figure in his great work, and 

 ■onfess that I know not how to institute any satisfactory comparison with those parts iu Papilio. It is just possible 

 hat the " dorsal process," in such forms as Ehyacophila, may be equivalent to my "uncus;" but of "scaphium" 

 L see not a trace. Possibly, too, the " inferior appendages," so largely developed in the same genus, may represent 

 :he " valves ;" but the resemblance is most evanescent. Tho penis seems formed on a plan wholly different. 



In one point my own observations agree with those of the learned author — the remarkable fact that no two species 

 feem to have the same forms of armature. 



My friend has been so kind as to send me his paper " On the Sexual Apparatus of the Male Acentropus " (Trans. 

 Ent. Soc. 1872). Looking at his figures, I should have been inclined to say, if I had not been told, that they repre- 

 sented the parts of some Papilio or Pieris. We seem to have the valve (a), with its dorsal moiety, indeed, absorbed 

 the tegumen projected into an uncus (6 and c) ; and the scaphium (d, e) small, but normal in form, connected basally 

 with the uncus, and bearing its usual lateral elevations, duly crowned with teeth or the characteristic aristaa. The 

 parallel is most curious. I should expect some form of harpc lurking within those appt ndices inferiors. 



nsi 



