PARNASSIUS II-IV. 



the following Sjjring, 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 fjxst disaj^j^earing." 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 larvje had died from 

 want of nourishment. 



Mr. INIead also state that, as a rule, the larger specimens of Smlnthevs, were 

 taken at the lower elevations. The fimales there also were usually white. On 

 the 8th and 9th of August, at Blue River, 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 s^^ots distinct. But the females were different 

 from any others taken by him, being characterized by broad and dark marginal 

 borders, the black sj)ots intense and the disks of a decided, though pale yellow, 

 the wings little obscured by grey, (see fig 2, ])\. 3.) Another of smaller size was 

 of a deeper yellow, and brilliantly adorned, (see fig. 3, ]>\. 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 tlie females 

 were melanized, the greater part of the surface of the wings being black and trans- 

 parent, (see figs. 4 and 5, jsl. 3.) The same jieculiarity 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 suj^ply of food on the mountain tojJS 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 i^rotectiou. 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. semidca, a blackish species, frequenting the Colo- 



