190 PROCEEDINGS OF THE ACADEMY OF [Jail.,. 



11. The Male Genital Armature of the North American 



Forms of Limenitis. 



. In former years I have felt, with many other naturaUsts, some- 

 suspicion of the conclusions based on a study of the male genitalia 

 of Lepidoptera. The organs are so complex and in parts so thin- 

 walled, so liable to be deformed by twisting and pressure, that it 

 seemed unlikely that they could escape alteration in the processes of 

 manipulation and mounting. Their shapes are such that a slight 

 difference in the angle at which a drawing is made or a photograph 

 taken makes all the difference to the result. I have, however, been 

 converted by my experience of the work of my friends Dr. Karl 

 Jordan and Dr. H. Eltringham. I have seen the latter naturalist 

 preparing and studying the same parts in different individuals again 

 and again until he was able to determine with complete certaintj^ 

 the actual form that is characteristic of the species or race. I there- 

 fore asked him if he would kindly help me by preparing and drawing 

 the genitalia of the North American forms of Limenitis. In asking 

 this favor, I was, all unconsciously, making ready for a most valuable 

 test of the validity of the method and its results. At the time when 

 Eltringham made his drawings we had no copy of Scudder's great 

 work (6) available, but, when they were finished, I borrowed the 

 volumes from the library of the Entomological Society of London. 

 I turned at once to Plate 33, representing the genitalia of the Canadian 

 and eastern North American species of Limenitis, and found that 

 the four figures (9, 11, 12, 15), prepared by Edward Burgess for 

 Scudder, might almost have been copied from Eltringham's drawings 

 or the drawings from the figures! Two careful pieces of work carried 

 out independently have led to precisely the same result. It will 

 therefore be admitted that we may safely accept the six figures oiii 

 the accompanying Plate V as the expression of the true structural 

 relationships in the different species. 



Figures 4, 5, and 6 on the right side of Plate V represent the 

 male genital armatures of species also figured by Scudder, save 

 that his L. astijanax (fig. 15) represents the eastern race and Eltring- 

 ham's (fig. 4) that from Arizona. But the form of the genitalia is 

 nearly the same, as may be seen by comparing the figures, allowing 

 of course for the difference in magnification. Eltringham's figures 

 also show with Scudder's the close resemblance between astijanax 

 and arthemis (fig. 5, Scudder's fig. 9). The two representations 

 of L. archippus are almost identical, save that Scudder (figs. 11 and 



