126 BTJLLETIIsr 15 7, TJ. S. NATIONAL, MUSEUM 



some of the males being much brighter than others, and some of the 

 females having the fore wings very dusky. 



De Lancey Gill informs me that in 1896 his son, Capt. Robert Gill, 

 captured a specimen in Rock Creek Park just beyond the limits of 

 the National Zoological Park that was rather larger than usual and 

 was entirely white on both surfaces. 



In my personal experience with this butterfly in the District I 

 have met with only minor variations. 



In a male taken by Hugh U. Clark at Cabin John on September 

 19, 1930 (pi. 58, fig. 1), the two buff spots normally present just 

 beyond the cell of the fore wings are absent, resulting in the appear- 

 ance of a conspicuous black patch. This feature is quite character- 

 istic of specimens of the middle American form nigrippus, at least 

 in certain localities, as is shown by one from Porto Rico and another 

 from Panama in the National Museum. In nigrippus, however, the 

 large spots in the apical portion of the fore wings are wdiite or 

 w^hitish instead of buff. 



In another male taken at the same time about 200 feet away (pi. 

 58, fig. 2) the black patch beyond the cell on the fore wings and the 

 dusky suffusion beyond this are lacking, the ground color of the 

 wings being continued to the apex, margined by a continuation of 

 the black outer border and of the black costal border and crossed 

 by veins narrowly black as in the rest of the wings. The buff spots 

 occur as usual, but they are on a brownish-orange background. The 

 black margin of the fore and hind wings has an outer row of small 

 white spots and an inner row of larger buff spots. This feature, 

 together with the reduction in the degree of black scaling on the 

 veins on the upper surface, brings to mind the subspecies erippus, as 

 illustrated especially by specimens in the National Museum from 

 Castro, State of Parana, Brazil. The dark inner border of the fore 

 wings and other features characteristic of the subspecies plexippus 

 as opposed to erippus are, however, present. 



Very frequently females show a sprinkling of bluish-white scales 

 on the costal margin of the fore wings near the base. These may 

 become numerous, when they are usually accompanied by a con- 

 siderable sprinkling of white scales in the inner portion of the inter- 

 sjDace between veins SM and Mi. There is sometimes in females a 

 sprinkling of white scales along the margins of the black stripe 

 forming the lower border of the cell on the hind wings, and along 

 the earlier portion of the three veinlets running down from this. 

 Females in which these white scales are numerous have a curiously 

 frosted appearance. 



The sexes of this butterfly are very nearly equal in numbers, the 

 males being slightly in excess. Of 118 caught at random, 64 (54 

 per cent) were males and 54 (46 per cent) were females. 



