344 The Scottish Naturalist. 



will take the case of Boarmia repandata. This insect is grey, 

 with a brownish tint, and its wings more or less traversed by 

 darker lines and bands. As a rule it rests on the trunks of trees, 

 and its colours very much resemble the bark, and so protect it 

 from observation. In the Outer Hebrides, however, there are 

 now no indigenous trees, though there were probably such 

 when Boarmia repandata first arrived there. When the trees got 

 scarcer the insect would have to repose on other objects, such 

 as stones. On these its colour would be no protection, and 

 consequently it would fall an easier prey to its enemies. But 

 those individuals which more resembled the stones in colour 

 would be less readily detected, and hence, in course of time, the 

 colours of all the Hebridean race of Boarmia repandata would 

 become modified till they became as they are at the present 

 day — namely, leaden-grey, with darker markings, and rarely a 

 very faint trace of brown, resembling very closely the gneiss 

 rock on which the insects rest. Thus has been brought about 

 the grey colour, which is a striking feature of many of the 

 Hebridean insects. 



The Shetland Isles are, as we have seen, the most remote of 

 the three groups from the mainland of Scotland. They were 

 also the first to become islands, and were hence cut off at a 

 comparatively early period from the north -flowing stream of 

 immigrants that peopled the other islands. New immigrants 

 at the present day must also be of rare occurrence. From this 

 it follows that the number of species in the Shetlands is small, 

 and that those that are there have fewer competitors to contend 

 with, and probably fewer enemies to protect themselves from. 

 Under these circumstances more and better defined varieties 

 have arisen and survived. 



It is very much to be desired that something should be 

 learned of the insects of the Faroe Islands. These, as well as 

 Iceland, derived their fauna and flora from Britain, and should, 

 for scientific purposes, be considered as forming part of it. 



Endromis versicolor. — Two fine specimens, now in the collection of Mr 

 George Sim, Gonrdas, Fyvie, were taken on birch at Ballater in May 1880, 

 by Mr Alexander Chivas, policeman, a local entomologist. — L. D. Dunbar, 

 Wick. 



