SATYRINAE: OENELS SEMIDEA. 145 



sively rare) and that a suj)i)leincntarv brood of tlie hutterflv annually 

 appears at this tinje. In further eonfinnation of sueh an irregularity was 

 the discovery of a caterpillar, curled up under a stone as if it had not yet 

 at all left its winter quarters, and still in its penultimate stage, on June 10, 

 1887 ; indeed it had evidently some time before it in that stage and fed on 

 grass for a fortnight, finally dying before another ecdysis ; it was only 12 mm. 

 long. It is evident that it had much the start of the caterpillars in their first 

 stage, and i)robable that pupation could have been reached before winter 

 set in, giving easy chance for the final change to butterflies the last of 

 May or early in June ; living chrysalids were found the same day and sev- 

 eral chrysalis-shells from which the imago had escaped, which it did not 

 seem probable could have passed the winter and come out in so fair a con- 

 dition ; but no butterflies were then seen, although careful watch was kept 

 for them. It is indeed possible that this caterpillar of the penultimate stage 

 was born from an early egg of the July butterflies of the previous year and 

 would have developed to a late July butterfly, in time to lay eggs the same 

 season, making the cycle in a single year. It is at any rate evident fi-om 

 these exceptional occurrences that we have much yet to learn of the history 

 of semidea. A visit to Mt. Washington on May 31 of the present year 

 when for over an hour the weather was warm, the air still, and the sun 

 seldom obscured, brought no sign of this butterfly. 



The European Alpine O. aello appears, says Meyer Diir, among the earli- 

 est butterflies of the Alps ; it is seen soon after the snow melts, first on 

 the lower grounds, at the end of May, last on the higher levels (corres- 

 ponding more nearly to those to which our species is restricted ) at about the 

 beginning of July ; and disappears in the same way from the end of June 

 below, to the end of the first week in August above. 



Habits, flight, etc. One would suppose that insects whose home is 

 almost always swept by the fiercest blasts would be [)rovided with jiowerful 

 wings, fitting them for strong and sustained flight : but the contrary is true ; 

 they can offer no resistance to the winds, and whenever they ascend more than 

 their accustomed two or three feet above the surface of the ground or pass 

 the shelter of some projecting ledge of rocks, they are whirled headlong to 

 immense distances until they can again hug the earth ; their flight is rather 

 sluggish and heavy and has less of the dancing movement than one is 

 accustomed to see in the Satyrids ; they are easily captured, though they 

 fly singly, never congregating, and have their devices to escape pursuit : 

 one is that when alarmed, and indeed at most times, they fly up or down 

 the slopes, rarely along them, rendering pursuit particularly difficult ; another 

 that they will rise in the air to get caught by the wind, which often takes 

 them out of sight in a moment ; one I once followed with my eye whirled 

 a good half-mile away, a thousand feet in the air, with a white cloud for a 

 background. But the neatest device of all is specially exasperating ; one 



