172 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



Notes. — The earliest individuals to appear are small and chalky 

 white with the tips of the wings pale gray (pi. 28, fig. 1 ; pi. 29, figs. 

 9, 10). In the males (pi. 29, figs. 9, 10) there is usually a small gray 

 spot on the fore wings in the center of the inner half of the inter- 

 space between veins Ms and Mg, and often a gray spot on the costal 

 margin of the hind wings ; but the wings may be wholly unmarked ex- 

 cept for the gray tips. The bases of the wings are rather extensively 

 and thickly studded with blackish scales. Early-spring females (pi. 

 28, fig. 1) are faint ivory white with the tips of the wings pale gray and 

 the spots very much reduced in size and poorly defined. The inner 

 portion of the wings, on the fore wings extending nearly to the end 

 of the cell, is heavily sprinkled with gray scales. 



About the middle of April larger butterflies appear, of which the 

 males have the inf uscation at the base of the wings less extensive and 

 the spots on the wings larger. These are of the same size as the 

 butterflies of the second brood (pi. 28, figs. 2, 3) and in color are 

 intei-mediate between the individuals of the two broods. 



Summer males (pi. 28, fig. 2) have the dark apical patch on the 

 fore wings considerably larger than spring males (pi. 29, fig. 9), and 

 also darker, especially the inner portion, where the scales may be 

 quite black. There is commonly a slender tooth of black running in- 

 ward along the lower radial vein. The spot on the fore wing is 

 larger and darker, especially on the underside, and there is a gray 

 spot below it near the inner border. The spot on the costal border 

 of the hind wings is large and dark. The inner portion of the wings 

 is much less heavily infuscated, and the lower surface of the hind 

 wings is less extensively stippled with dark scales — indeed, in some 

 examples these may be very few. Occasionally summer individuals 

 occur in which the dark apical patch is reduced, the spot on the fore 

 wings is small, and the faint spot below it and that on the costal 

 border of the hind wings are merely vestigial; but these have 

 the other features characteristic of the summer form. In the sum- 

 mer females the dark apical area of the fore wings is more exten- 

 sive than in spring individuals, and much darker. It either extends 

 so as to include the end of the lower radial vein, reaching the outer 

 margin halfway between the lower radial and M3, in which case M2 

 may be dusky at the tip, or it terminates in the interspace between 

 the upper and lower radials, in which case a narrow dark triangle ex- 

 tends inward for some distance along M3; this triangle may be 

 quite isolated, or it may be united basally with the patch above. 

 The two spots on the fore wing and the spot on the hind wing are 

 very much larger and darker than in the spring form. There is 

 commonly a narrow dusky line extending inward from beneath the 

 middle of the lower spot along the inner border, and rarely the two 



