b THE ENTOMOLOGIST S RECORD. 



In these cases what is the incentive ? My own experience on this point 

 is, as already mentioned, limited to two instances ; and one of them 

 (P. teams) is an insect which often is found within the Alpine region. 

 It therefore, to a certain degree, may have developed (or retained) the 

 habits of an Alpine species. But the essentially lowland species which 

 exhibit a tendency to lay in such circumstances, cannot be accounted 

 for in that way ; and though there can be no doubt that such occurrences 

 are very rare, I think one can but regard them as the re-assertion and 

 adaption of a natural instinct, once essential to the species in question, 

 or rather to the ancestral type from which it was evolved, which in a 

 remote past existed under very different climatic conditions. That 

 after such a lapse of time as this concludes, the instinct still asserts 

 itself, no matter how slightly, is suggestive that such a fac llty as we 

 have been considering, would be in no wise impaired by lying in 

 abeyance through ten, or many more generations. 



Another contention, which may be brought forward, is that if 

 Alpine species can survive burial they do not need to lay in that con- 

 dition, but can resume their task when liberated again. ■ To accept 

 that contention we must assume that they can live under snow for an 

 indefinite period ; in the case of those species located above 6500ft. for 

 perhaps as much as fourteen days, and for all species for seven days 

 and nights; the longest period of which I have obtained authentic in- 

 formation of snow lying in July, at 5000 ft. This, it does not seem to 

 me, we can do, for although it is impossible to put a fixed limit to the 

 length of time which they may survive, there is no doubt that, as has 

 been already noted, even during a period of no longer than forty-eight 

 hours, a certain number of individuals succumb, and the complete want 

 of butterflies, in especially poor summers, which has been observed on 

 occasions by collectors in the high Alps, is probably to be directly 

 attributed to a longer spell of snow than they can survive. That when 

 only quite a short time buried it is likely no eggs are laid, I have already 

 suggested, but when it comes to a matter of days, I feel sure if the 

 eggs were not laid, they would never be laid at all. Both these points 

 are borne out by the fact that in boxes I have never found an egg laid, 

 unless the butterfly had been enclosed for the best part of a day. 



Again, in the ca?e of late summer species : it is not an uncommon 

 occurrence at altitudes over 6,000 ft. for snow falling in late August to 

 be followed by successive falls at short intervals, so that the first fall 

 has not completely melted before the next covers it again, and so it 

 passes into winter without a break. Further, in considering the length 

 of time any species can be buried and survive, one must remember 

 that the depth of snow covering them may greatly affect this. The 

 average depth of summer falls at altitudes between 5000 and 6000 ft. 

 rarely exceeds five or six inches, but it can be double that (see Mr. 

 Curwen's note already quoted), and of course at higher levels it may 

 frequently be so. It is quite possible that a quite short period under 

 a greater depth, might be no more detrimental to the insects than a 

 longer period under less ; but data on this question are wholly wanting. 



One more point arises which might be used as an argument 

 against my theory. The buried butterfly, of necessity, lays its eggs on 

 any available surface. What would become of the young larva? on 

 hatching from these eggs, possibly situated on a rock, or some plant, 

 other than their foodplant ? With species with very specialised food- 



