1914.] NATURAL SCIENCES OF PHILADELPHIA. 183 



« 



of the former but not of the latter from the upper surface of the 

 aUied archippus. On the other hand, the development on the under 

 as compared with the upper surface is greater in the black than the 

 white. In both sexes there is a tendency, as in archippus, to throw 

 the white spots on the under surface of the hind wing into relief by 

 an inner edging — a darkened shade of the ground-color in areas 

 2, 3, 4, and 5, still darker and often black in areas 6 and 7. This 

 feature probably represents the black inner border of the white 

 discal band in the non-mimetic ancestor. 



When the 32 specimens, omitting the 2 taken in June and July, 

 recorded in the table on p. 180, are arranged according to their two 

 broods — the 15 March and April specimens together and the 17 

 September and October together — it is seen that there is a small but 

 distinct seasonal difference in the development of the trace of the 

 white discal band of the hind wing and its black outer border. The 

 spring brood is in this respect distinctly the more ancestral, bearing 

 on the average stronger traces of the pattern of weidemeyeri and 

 arthemis. This is true of the females as well as the males, as may be 

 inferred from the foUownng statement: 



Females (spring brood = 4, autumn brood = 5). — The only 2 

 specimens with evanescent band and border bear the dates Sept. 11, 

 1911, and Oct. 10, 1910. The most reduced band of the spring brood 

 is seen in the Tucson specimen, April 9, 1896. In all the remaining 

 4 spring females, the band and, in all but one, the border is distinctly 

 stronger than in either of the 2 remaining autumn females. 



Males (spring brood = 10, autumn brood = 13). — It is extremely 

 difficult to classify the degree of development of the band and border 

 ■ — there is a complete and gradual transition. There is, however, a 

 marked difference at both ends of the scale between the two broods. 

 The most evanescent white bands are seen in 6 autumn males. In 

 all these the feature is more reduced than in any spring male. Very 

 small and reduced bands are found in 3 males of each brood. Beyond 

 these there is the most gradual transition to the highest degree of 

 development found in the sex, and among these we find by far the 

 highest in a specimen captured April 22, 1911, while 2 other spring 

 males are rather beyond any of the autumn brood. Considering 

 the black border separately, the difference is even more marked, for 

 this feature is evanescent in 4 of the autumn brood and none of the 

 spring, while the next 4 are equalled and on the whole slightly 

 exceeded by the 4 spring specimens in which the feature is least de- 

 veloped. The black border is more highly developed in 4 of the spring 



