290 The Scottish Naturalist. 



insects for sale — to visit fresh fields and pastures new in the 

 hope of finding species or varieties hitherto undiscovered in 

 this country ; and hence districts which, from lack of zeal on 

 the part of the amateur — who, when he goes collecting, seems 

 rather to prefer the certainty of a known to the uncertainty of 

 an unknown locality, and to take onine. ignotum pro horrifico, 

 — have been left unexplored, have their lepidopterous fauna 

 more or less thoroughly investigated. 



Amongst localities thus visited within the last few years are 

 the Orkney Isles, the Shetland Isles, and the Outer Hebrides. 

 It is true that these were not altogether unexplored by lepidop- 

 terologists, but much remained (and probably still remains) to 

 be done, and a considerable amount of information has now 

 been obtained. 



The fauna and flora of islands — considered either apart by 

 themselves or in relation to the productions of the nearest conti- 

 nent or larger island — embrace subjects full of interest in many 

 respects, — an interest which increases with the distance of 

 the island from other land. Even Britain itself, closely situ- 

 ated as. it is to continental Europe, has a fauna and flora which, 

 considered from the insular point of view, have many points 

 of interest. It was therefore to be expected — and this expecta- 

 tion has not been disappointed — that the islands which lie 

 off the British coasts would present, as regards their fauna, 

 still more remarkable features. 



* 



The materials for the following paper have been mostly taken 

 from articles by Mr Jenner Weir in ' The Entomologist ' (vol. xiii. 

 pp. 249 and 289 ; xiv. pp. 218 and 278; and xv. p. 1.), founded 

 on collections made for Messrs Meek and M'Arthur in the Island 

 of Hoy, in Orkney, the Mainland in Shetland, and the Lewis in 

 the Outer Hebrides. 



Hoy is about eight miles from the coast of Caithness, and 

 geologically belongs to the Old Red Sandstone formation. 

 The average temperature of the Orkneys varies from 38 in 

 February to 55 14' in July; and the rainfall is about 37.22 

 inches. 



The Shetlands (excluding Fair Isle) are separated by about 

 60 miles of sea from the Orkneys, — Lerwick, the chief town, being 

 171 miles from Wick. The geological formation is chiefly gneiss 

 and granite. 



The Outer Hebrides are similar in geological formation to 

 the Shetlands, but are two degrees farther south and five degrees 



