1914.] NATURAL SCIENCES OF PHILADELPHIA. 18o> 



lightened in tint, represent the two more conspicuous white spots 

 occupying nearly the same position in Anosin [Danaida]" (31, 456-7). 

 Now that I have had the advantage of studying obsoleta, and have 

 re-examined archippus in the light of the new experience, I find that 

 a few examples do possess a very faint trace of the reddish patches of 

 arthemis. In these vestiges as in so many other features in the pattern 

 we are led to conclude that obsoleta represents an older stage in the 

 evolution of archippus. 



The fore wing. — The inner edge of the angulated black outer 

 border of the white band of arlhemis and weidemeyeri runs from the 

 costa to the inner margin of the wing, near but well within the pos- 

 terior angle, although it is broadened so far that its outer edge enters 

 this angle; in most specimens of archippus it runs to the junction of 

 the middle and posterior third of the outer (hind) margin (31, 

 p. 457). Some females, however, approach the condition of obsoleta, 

 which is generally far nearer in this respect to the pattern of arthemis 

 and weidemeyeri. In obsoleta the direction of the vestigial black 

 outer border, which, except near the costa, is evanescent on the 

 upper surface, can be easily traced by fixing the attention on the 

 outer ends of the four prominent white spots in areas 3, 4, 5, and 6. 

 With this as guide, the eye is led on to an evanescent white spot nearly 

 always present in area 2, and in certain individuals to the faint 

 continuation of the black line towards the posterior angle. The 

 angle made with the costa is very different from that of archippus. 

 The black line is usually far more distinct on the under surface, and 

 here it may be seen in many specimens that the direction changes 

 abruptly in area lb, becoming parallel with the outer margin and 

 leading to a termination on the inner margin within, and often well 

 within the posterior angle. In well-marked specimens, especially 

 in the females, the black line is seen to lead to the outer end of a white 

 linear mark close to the inner margin in area la (see p. 186). Faint 

 vestiges of the former white band can even be made out in lb on 

 the under surface of a few individuals. There is great variation in 

 the position of the black line in 11). In most males it unites with 

 and continues as a broadening of the black margin. 



The white spots which represent the costal half of the white band 

 of arthemis and weidemeyeri are far better developed in obsoleta than 

 in archippus. In the latter the spots are 2 to 4 in number, the last 

 being very small. In obsoleta there are always 4 large and distinct 

 spots, especially well developed in the female, while a minute 5tli 

 spot, already mentioned as placed in area 2, is nearly always present 



