184 PROCEEDINGS OF THE ACADEMY OF [Jan., 



brood than in any of the autumn. This detailed comparison has 

 been extraordinarily difficult to make, because of the perfect transi- 

 tion and the minute shades of difference. When the attempt was 

 made to express the difference, the specimens grouped themselves 

 into fours in an irritating and unnatural manner. It might perhaps 

 have been wiser to attempt no analysis of so transitional a feature, 

 but to be contented with the statement that a distinct difference 

 exists at both ends of the scale, the band and border of the most 

 strongly marked specimens being decidedly more developed in 'the 

 spring brood, while the reduction of these features in the least strongly 

 marked specimens was carried distinctly further in the autumn 

 brood. I cannot but think, however, that my attempts at an 

 analytical comparison, whatever faults there may be in the details, 

 are a truer expression of the facts. 



An interesting difference between the. upper surface of ohsoleta 

 and that of archippus is common to both fore and hind wings, viz., 

 the far more heavily blackened veins gained by the latter in mimicry 

 of D. plexippus. Floridensis here shows its origin from archippus, 

 for it retains the darkening along the veins, although out of place in a 

 mimic of D. berenice. No such evidence of having passed through an 

 archippus stage is to be seen on the upper surface of ohsoleta. The 

 veins are heavily blackened on the under surface of the hind wing 

 in all three mimics, in evident likeness to their respective models, 

 although ohsoleta in this respect is less darkened and a less perfect 

 mimic than the other two. 



In certain specimens of ohsoleta there is to be seen on the hind wing 

 under surface two largish rich brown sharply outlined patches, one in 

 the cell and one near the base of area 7. On the basal side of each 

 patch is a white spot and a white suffusion commonly surrounds the 

 projection of the precostal into area 8. These elements tend to 

 become evanescent together and distinct together, acting like a single 

 feature. Slight traces of these markings can probably be found on 

 every fresh specimen. They were remarkably pronounced in the 

 female taken Sept. 5, 1911 (p. 181). These vestiges, except in one 

 respect, resemble the well-known basal pattern of orthemis far more 

 closely than that of weidemeyeri. The pale elements are, however, 

 for the most part blue in arthemis, but nearly white in loeidemeyeri, 

 and therefore in this respect nearer to ohsoleta. Archippus has 

 advanced further from the ancestral forms than ohsoleta, for "the 

 basal red patches have vanished, but the pale blue marks in and on 

 the costal side [area 7] of the base of the cell are retained, and, 



