NOTES ON CORSICAN BUTTERFLIES. 117 



rei3resented ; the genus Melitcsa, though represented hy at least 

 a dozen species on the mainland ; and, most striking of all, the 

 gen as Erebia, though upwards of twenty species occur in 

 Switzerland and South Eastern France. I was at first very 

 puzzled to account for the complete absence of all mountain 

 butterllies ; and the only explanation that I can offer is, that the 

 island was isolated from the mainland before the increasing cold 

 in the arctic regions, which was to culminate in a glacial epoch 

 for Europe, had driven the species which now inhabit the alps of 

 Europe from the circumpolar region, whence they probably 

 originated. From the number of genera common to the 

 palffiarctic and nearctic regions, the greater part of the European 

 fauna appears to have been of circumpolar origin ; but probably 

 a very much less degree of cold would have sufficed to drive 

 many of the species south, those which are at present found only 

 in the mountains of Europe being the last to retreat before it. 

 Considerable traces of local glaciation exist in the island itself, 

 as the presence of alpine tarns in rock basins under the steep 

 cliffs near the summits of the higher peaks, such as the Monte 

 Eotondo and the Monte d'Oro, and the smooth rounded surfaces 

 presented by the higher slopes of the mountains ; but there is 

 nothing to show that the glaciers were of any extent, and, as 

 pointed out by Mr. Wallace in a recent article in the ' Fortnightly,' 

 no lake basins occur in the island in the lower valleys. The 

 cold, however, may have been sufficiently intense to have 

 destroyed any species of the Eur- African fauna which may have 

 inhabited the island. The only African butterfly at present found 

 there is Charaxes jasius, which is also found in the South of 

 France. I gathered from a French Coleopterist that there was 

 a certain proportion of African forms among the beetles. 



The entire absence of alpine butterflies is but one of the 

 features of interest that the fauna presents, and probably no- 

 where so close at hand can the gradation from species identical 

 with those on the mainland " through slight varieties, local forms 

 and insular races to well-defined species," to use Mr. Wallace's 

 words, be so well studied. 



The same remarks apply, of course, to the sister island of 

 Sardinia, from which the isolation must be comparatively recent, 

 as the straits of Bonifazio are only ten miles across at the 

 present time. I have not, however, been able to obtain a 

 Corsican record of Epinephdc nurag, which may possibly be 

 confined to Sardinia. It appears to he rare in collections, and 

 was described by Ghiliani from Sardinian specimens. 



Slight variation is exhibited by a number of species found in 

 the island, and many of these are noted by Mr. Standen, 

 e.g., Lycceiia baton, L.asirarche, Vanessa c-albiim, and Epincphele 

 ianira, to which might be added Argynnis paphia Ya,Y. anargyi-a, 

 which, although not peculiar to the island, is, I believe, more 



