August, 1871.| 49 
in Europe, and Smerinthus cecimaculatus differs little from our Simerin- 
thus ocellatus, saving that the upper wings are crenate at the hind mar- 
gin as in S. populi. 
This, however, is a digression from the main subject of our paper ; 
yet, before quitting it entirely, it may be as well for us to bear in mind 
that it is a pure assumption to state that the migration was from 
Europe to America, there may have been an endosmose into Europe, 
as well as an exosmose from it. 
5. The fifth group, Autochthones, insects peculiar to our islands, is 
of course full of interest, yet they are few, and present no special 
characters. 
Amongst the diurnal Lepidoptera, Polyommatus Artaxerxes is our 
only example, and this is regarded by most as a northern variety of 
Agestis,—which, indeed, the intermediate Salmacis seems to indicate : 
yet that such a remarkable variety should be found in Scotland only, 
whilst the usual type occurs in Sweden, Norway, and Northern Prussia, 
is a fact quite as strange and worthy of note as if it were a fixed species. 
The dark forms of JMelitea Artemis are, as far as I can discover, also 
unknown on the continent, but I have never seen Scandinavian 
specimens. 
Amongst the Nocturni there are two peculiar to our islands, 
Lithosia sericea and Lithosia griseola, var. stramineola. Lithosia sericea, 
very limited in its distribution in England, has not long been re- 
marked as a distinct species, and may possibly have been overlooked. 
The variety stramineola is not, like Artaxerxes, in any way climatic, since 
it occurs alike in Devonshire and in the fens of Norfolk: it is, indeed, 
one of those strange variations in which an aberrant form of a species 
belonging to one group somewhat approaches another group of the 
same genus. 
Amongst the Geometre there is no species peculiar to the British 
Isles, and the same may be said of the Pseudo-bombycide and Drepanule. 
Agrotis Ashworthii seems unknown on the continent; it is a 
western species, and may be yet found in Spain. It is a species of 
much interest, confined to a little tract in Wales, the larva differing 
much from that of its nearest British ally, Agrotis lucernea, from which 
it is widely distinct. 
Noctua subrosea is doubtful, as it has been taken in Russia. It 
is now very rare in England, and perhaps may soon be extinct. 
Dianthecia Barrett: the discovery of a peculiar British Dianthecia 
in Ireland and the Isle of Man, which for some reason or other unknown 
