SATVUIXAK: OENICIS SEMIDKA. 143 



the :ii(l of others, and am siii-c that the i)hi<;e« chosen by the hirva for pupa- 

 tion are exactly those cliosen by it for daily concealment, namely, the under 

 side of surface stones, which rest either upon another stone or upon some 

 other thing than the loose, disintegrated, gr:i\elly rock which least retains 

 moisture; a level, damp and cool, protected spot is that most sought for; 

 here the caterpillar rests upon the lower surface with its roof grazing its 

 hack, and pushing away whatever may intcrfci-c with the smoothness of 

 the spot changes to chrysalis without further ado. Unless some moss be 

 at hand there is no semblance even of a cell ; and even where moss is 

 present there is sometimes no mark of a cell ; and when found is due 

 simi)ly to the movements of the caterpillar, with an amount of silk scarcely 

 enough to enable one to remove it and in any way })reser^•e the form ; no 

 threads indeed are visible without a lens ; and I have but once — and that 

 was last spring — found a cell which was anywhere near complete, and 

 this one lacked an upper surface ; when the stone which served that 

 purpose was removed, the luico^ered cell was undisturbed by it, slun\- 

 ing that no threads were attached to the covering stone. The cater- 

 pillar was lying on its back when found, ^Nfay 31, and changed to chrysalis 

 on June 2 in the valley below. Was then carried to the sea level at 

 Cambridge, and the butterfly emerged on the early morning of the 19th. 

 As this is earlier than its normal time on the mountain, its appearance 

 was doubtless hastened by the favorable warmth of the lower level ; four 

 weeks is more probably its natural period. 



Life history. This is a single-brooded butterfly ; it usually begins to 

 appear on Mt. Washington ^ery early — the first week — in July, becomes 

 exceedingly abundant before the middle of the month and continues until 

 about the second week in August. On Sierra Blanca, in Colorado, I took 

 a single rubbed male as late as August 29 and a tolerably fresh male on ^It. 

 Lincoln on August 13. ]\Ir. Bruce took them early in July. ]\Ir. Sanborn 

 gave July 4 as its earliest appearance in New Hampshire in 18(J9, and only 

 one more specimen was seen before the 9th, although the weather was 

 favorable. Morrison says "the first specimens appeai-ed about July 1 

 [in 1874] and in a few days it became very abundant." ]\Ir. Dimmock 

 took one the same year on June 2S and several on July 4 and H. These 

 may serve, I think, as average dates, and the butterflies will best be taken 

 in the second and third weeks in July ; they apparently lay most of their 

 eggs during the last week of July ; caterpillars have been found by ^Ir. 

 Whitney, the late ^Messrs. Sanborn and Shurtleflf, and by myself, nearly 

 full-grow-n, between the 20th of July and the 2d of August, and others cer- 

 tainly full-grown on August 19 and in September. These must certainly 

 have been born the previous year, as the eggs do not hatch before the first 

 of ,\ugust ; and as all living chrysalids that have been found have been 

 taken in the earlier part of the season, between June 10 and the early part 



