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but who, nevertheless, have not very extensive habits, 
may be mentioned Hibernia aurantiaria and defoliaria, of 
which Gaetke has recorded remarkable migration. These 
are Moths appearing in late autumn and early winter, and, 
curiously enough, it is the males only that migrate, as the 
females are wingless. The migration cannot therefore be 
intended to promote the extension of the habitat ; but as in 
the case of the Northern Lemming, is probably connected 
with the over production of the species in its natural habitat 
owing to unusually favourable climatic conditions. The 
order Lepidoptera affords many interesting proofs of the 
geological changes which have taken place on the surface 
of the globe. Here is a small Burnet Moth, Zygcena exulans, 
which was discovered on the Aberdeenshire mountains 
above Braemar about forty years since in a very limited 
locality between 2000 and 3000 feet above the sea level. 
It is found also in the High Alps, Pyrenees, and mountains of 
Scandinavia. In the Alps I think it is not much below 
6000 feet ; but on Monte Moro Pass, at an elevation of about 
8000 feet, I remember finding it most abundant. The 
Scandinavian specimens differ somewhat from the Alpine, 
and have been described under the varietal name of vanadis. 
It is to this variety, as might be expected, that the Scottish 
specimens belong. Now this little moth speaks most plainly 
of a glacial period. As the great ice sheet, which at one time 
covered the Northern Hemisphere, melted, and the plains 
became warmer, the cold-loving plants and animals retreated 
up the mountains, and in this particular instance a little 
colony of these Burnet Moths became cut off from the rest 
of their fellows who migrated to Scandinavia, and were 
stranded on the Aberdeenshire mountains ; hence the name 
of exulans , the exile, is a very appropriate one. In connection 
with this instance, I may mention a confirmatory case which 
came under my notice in the island of Corsica a few years 
since. I was in a locality in the interior of the island and 
