DISTRIBUTE INSECT VARIETY. 279 



insects are scarcer and produce fewer annual broods. Nor is this 

 but a phase of a widesj)read agency^ which a consignment of 

 butterflies and papilionaceous moths from the temperate airs of 

 southern France that vanish in the south of England or Scotland, 

 or of a series of the same taken at different mountain altitudes, 

 or of a series of the same that push their migrations outwards to 

 Northern Africa and India, alike will prove to establish and 

 confirm as regards the old world area. 



Firstly, we shall find the forms themselves vary. In Southern 

 Europe our clipped-wing little Clouded Yellows of railway banks 

 and woodland Black- veined White Butterflies, float on ampler and 

 more rounded vans, whose redundancy seems even to impair their 

 powers of locomotion. Then light and heat, as observation and 

 experiment alike confirm, rule the colour scale. The pale white of 

 day-flying moths, as we see it in the Common Heath Moth of 

 the Highland heather and in the male Bordered White 

 {F. piniaria) of Perthshire fir woods, passes into a rich yellow 

 among the spruce and furze of the Hampshire New Forest. The 

 dirty white of an Argyleshire Speckled Wood Butterfly becomes 

 in England yellow, and in South Europe fulvous; and here 

 enlargement of the speckles causes the dark ground in one variety 

 to resolve itself into lines, giving the butterfly the look of its 

 congener of the hedgerows. Then it has become an established 

 axiom that those colour- bands with charming ocellated spots, that 

 so enhance the butterfly kind, should everywhere vary, and in 

 localities vanish ; and many drab and brown wings fluttering 

 among grass and shade from time to time have exhibited the 

 hillsman sports that have caused a cry of new species, or prompted 

 experts to enter on description where others see but variety. 

 The Large Heath Butterfly may be reckoned among these. This 

 kind in the north of England, at an elevation of two thousand 

 feet, according to Mr. T. Marshall, and in some parts of Ireland, 

 according to Mr. Birchall, has the eyes painted on its sandy 

 wings greatly decreased in number ; and on the Perthshire moun- 

 tains, conjointly with our English type, an aberration is some- 

 times seen even less ocellated; and this anomaly we find has 

 established itself in Lapland as the local form Isis of the species, 

 the most boreal variation. The Mountain Ringlet [Cassiope], 

 another prize of our southern collectors, varies much in the 



