PARNASSIUS II— IV. 
the following Spring, and on the 5th of September, he writes from Kenosha. House, 
“All the leaves are falling or have changed to their Autumnal tints and naturally 
the butterflies are fast disappearing.” Mr. Mead informs me since his return, that, 
on the 10th of January, in New York, some of these eggs which had been of late 
kept in a warm room were found to have hatched, but the larvae had died from 
want of nourishment. 
Mr. Mead also state that, as a rule, the larger specimens of Smintheus, were 
taken at the lower elevations. The females there also were usually white. On 
the 8th and 9th of August, at Blue Biver, in the Middle Park, at an elevation 
of about 9000 feet, six specimens were taken, the males large and beautifully 
marked, the colors bright and black spots distinct. But the females were different 
from any others taken by him, being characterized by broad and dark marginal 
borders, the black spots intense and the disks of a decided, though pale yellow, 
the wings little obscured by grey, (see fig 2, pi. 3.) Another of smaller size was 
of a deeper yellow, and brilliantly adorned, (see fig. 3, pi. 3.) 
On the 16th of August, several specimens were taken on the top of Berthoud’s 
Pass, at 11,300 feet, where was a grassy space of two or three acres extent. Others 
were taken on the Peaks around Twin Lakes, at about 12,000 feet. The males did 
not differ from the usual type, except in size, (see fig. 1. pi. 3,) but the females 
were melanized, the greater part of the surface of the wings being black and trans- 
parent, (see figs. 4 and 5, pi. 3.) The same peculiarity had been noticed in the 
specimens taken on 5th of August, on the Continental Divide, elevation 11,000 
feet, on the trail from Georgetown to Middle Park and near Gray’s Peaks. Much 
of the difference therefore existing between the size of these insects is owing, as 
might be expected, to the difference in elevation at which they are found, because 
the severity of the climate or the scanty supply of food on the mountain tops would 
restrict the growth of the larvae. But why the general coloration of the male should 
be identical at all altitudes while the females present such differences or why at 
great elevations there is such a tendency to melanization in the females alone is 
not clear unless in some way serving for protection. On this point Mr. Mead 
writes, “On the bleak summits of the peaks vegetation is scanty and the general as- 
pect is dark and sombre. The rocks themselves are dark-colored, and the lichens 
which nearly cover them are black and give the prevailing color. Lower down where 
the “bunch” and “gramma” grass can thrive the prevailing tint is pale brown, even 
during the height of the growing season, as the dead spears of the last years growth 
are remarkably persistent.” Perhaps this may help to explain the melanism of the 
Parnassius females found in the upper regions. A somewhat similar illustration 
may be found in Chionobas. C. semidea, a blackish species, frequenting the Colo- 
