11 
which is widened toward the apex of each joint, and there sends 
downward a transverse band connecting this white line with the white 
under side. The knob is flattened or spoon-shaped and black on the 
concave inner side, white on the lower edge and outer side; the upper 
part of this side being sprinkled with black scales which sometimes 
form bands of this color, the tips pale yellow. The thorax is black 
and clothed with soft hairs of a white or bluish white color. The ab¬ 
domen is black and covered with white appressed scales, less dense upon 
the back; its under side white and coated with white scales. The legs 
are covered with white scales, and the under side of the thighs with 
white hairs; and there is frequently a black stripe on the thighs and 
one or two slender black lines On the shanks and feet. The wings 
are white and at their bases dusted more or less with black scales. 
The fore wings frequently have black scales sprinkled along their 
outer or costal border its whole length. At their tips is a large tri¬ 
angular grayish black spot, which is longer on the outer than on the 
hind side, and on its inner side straight!sh, frequently with a con¬ 
cavity towards its inner end. In the female this spot is larger, but 
effaced on its inner end, whereby it has more of a squarish than a 
triangular form. Slightly beyond the center of these wings is a large 
black dot or round spot; and between this and the inner edge, in 
the female, is a second spot, which is usually smaller and less regu¬ 
lar in form, with its edges more indefinite. And in this sex is fre¬ 
quently a faint gray streak on the inner border of these wings, extend¬ 
ing from opposite the inner spot forward toward the base. The hind 
wings in both sexes have a black spot on the outer margin a lit¬ 
tle back of the middle, which is smaller than those on the upper 
wings, and its more indefinite. On the underside, the forewings are 
white and sprinkled with black scales at the base and along the outer 
border sometimes to the middle. Along the innerside of the rib-vein 
toward the base is a broad stain of yellow, more distinct in the fe¬ 
males. The tips are pale yellow, and in both sexes there are two 
black spots, corresponding with those on the upper side in the female, 
but commonly smaller. The hind wings are pale yellow, and dusted 
over Avith small black scales, which are more numerous toward the 
base; the outer edge is brighter yellow near the base, and no ves¬ 
tiges of the black spot of the upper side are here visible in either 
sex..” 
Curtis’s description of the species as observed in England is as 
follows: 
“The male is white, the superior wings have black tips dusted with 
white, and the inferior wings have a black spot on the upper 
edge: The female is similar, but has tAVo large black spots likewise 
be} T ond the center of the superior wings; under side of same Avhite, 
the apex yellow, and two black spots beyond the middle, the lower 
one sometimes nearly obliterated; inferior wings yellow, freckled with 
black; length of male, 8 lines; expanse about 2 inches; the female is 
larger and sometimes of a duller color; but I posess a male taken ' 
near Oldham, in Lancashire, which has all the wings of a bright yel¬ 
low color.” 
The female butterfly deposits her eggs singly here and there 
usually upon the under side of the leaves, not in clusters as do some 
other species of the same generic group; but she does not confine 
herself to this part of the leaf as the edge and upper side are often 
