TJie Scottish Naturalist. 151 



Anarta melanoJ>a — Vaccinium and Arctostaphylos. 

 II cordigera — Arctostaphylos uva-ursi (&c. ?). 

 Psodos coracina — Calluna ? 

 Scopida uliginosalis — 

 Scoparia alpina — Mosses ? 



II gracilaiis — Mosses ? 

 Cravibus fti7'catelhis — Grasses ? mosses ? 

 Penthina Staintontiana — Vaccinium nryrtillus. 



M Grevilleana — Arctostaphylos ? 

 Sericoris irriguajia — 

 Hivainmerdamia nanivora — Betula nana. 

 Zelleria saxifragcE — Saxifraga aizoides, &c. 



Of these plants, the grasses and Betula nana are wind-fer- 

 tilised ; Vaccinium^ Arctostaphylos, and Saxifraga are generally 

 insect-fertilised. 



It may be argued that the insects in question, being furnished 

 with wings, were not dependent on a land-connection with con- 

 tinental Europe for their introduction into Britain ; and it is 

 quite possible that some of them may have found their way 

 across the narrow seas. Whether in that case they would make 

 good their footing, would depend on whether their own peculiar 

 food-plants had become established. That some plants had 

 reached this country before the land-connection took place is 

 very likely, but that the majority of the plants crossed by land 

 (or at least when the water-barrier was much narrower) seems 

 more probable. Another objection to a theory of passage across 

 the sea is that most of the insects in question seem to be — now, 

 at least — of a very unmigratory disposition ; and unless their 

 habits in former times were different, they would not be likely to 

 venture across the sea. On the mountains there are many places, 

 which appear as suitable as those inhabited by the various species, 

 which remain untenanted ; and though it would be very rash to 

 say that these spots will remain untenanted, yet if the insects in 

 question had been of a roving disposition, they would probably 

 have colonised or recolonised them. As for involuntary migra- 

 tion, by means of the wind-currents, these mountain insects seem 

 to have a wholesome dread of wind, and will not as a rule ven- 

 ture out in a breeze unless compelled by dire necessity, either 

 concealing themselves in the scanty herbage or taking shelter 

 under stones, as I have seen Psodos do. Many of the lowland 

 insects get caught by the wind and blown on to the mountains, 

 as I observed by finding large quantities of them scattered on 

 snow-fields on one of our hills. I was at the time especially 



