56 
spot, and so I cannot verify that the geological conditions are identical, 
but that seems to be very probable. The only other locality I have 
heard of, is that recorded by Mr. Nicholson who has specimens from 
near Pontresina, some 60 miles almost due east. I do not know 
what the geological conditions may be in its eastern habitat. At 
Campolungo there are a good many rare plants, but whether there 
are any rare and local grasses that might perchance be its food- 
plant and thus account for the localisation of the butterfly I do not 
know. We found on the same ground as E.Jiavofasciata, Psodos quadri- 
faria flying freely, interesting from the circumstance that with 
t'atasta auriciliella and some other alpine forms, it has a disposition of 
yellow markings on its wings, which seems calculated to secure the 
same effect and possibly the same objects that E . Jiavofasciata looks for 
in its peculiar markings. Amongst the butterflies met with at Fusio 
was Erebia mnestra ; it was only coming out and a few males were 
taken, generally in fine condition, it was most abundant in one or two 
little gullies at about 6000ft. on the sides of the Campolungo pass, flying 
along with Melampias epiphron and swarms of Erebia tyndarux. We again 
met with this butterfly at about 5500ft., near Macugnaga, in a damp 
opening in the wood by a stream, again only males were taken (July 
20th). On the Simplon about 5500ft. we once more found males in 
very fair condition along the roadside, but no trace of females. In the 
Laquinthal, at the same date males were found in very worn condition, 
and here females were met with (July 80th). At Evolena, between 
Ferpecle and the Alp Bricolla, at 7200ft., the species was found on a 
limited slope in great abundance, both sexes occurred, the males perhaps 
more freely, the females were a little worn, most of the males very much so 
(August 10th). The female of this species is regarded as very much 
rarer than the male, and this is the only place where I have taken it 
freely. It is, of course, as everyone knows, the rule for the males of 
nearly all lepidoptera to appear before the females, and the fact is 
nowhere perhaps more forced on one’s notice than amongst the Erebiae, 
and the effect very often is to leave one with the impression that the 
males and females occupy different localities. At Simplon, where males 
were not uncommon, we asked ourselves as to mnestra, where were the 
females ? The answer no doubt was, not yet emerged, although they 
were already rather worn in the adjacent Laquinthal. I have been 
very much impressed with the same facts as to E. euryale, at Mendel 
and some other places. The males would be abundant wherever one 
went, but no females could be seen, and this continued for ten days or 
a fortnight, then a female or two would appear, then moving on to 
another locality one would find females abundant but hardly a male 
could be found. I doubt very much whether we understand more than 
very superficially anything about the explanation of these facts. That 
the male should come out before the female, and have already powers 
of vigorous flight by the time she emerges, seems easily understood and 
to be distinctly advantageous. But that he should emerge a fortnight 
before the female and that many should perish and the majority be 
torn and wasted by that date, and that females should still emerge 
when the males are represented by only a few exhausted individuals, is 
difficult to understand. Also what comes of sexual selection, which 
we must look for amongst butterflies, if anywhere in insects, if the 
females have little or no chance of ever seeing a freshly emerged male 
