132 THE BUTTERFLIES OF XEW ENGLAND. 



to the siiimnit ; but an actual capture would be necessary to establish such 

 a ftict. It, too, is regarded by some as merely a variety of another species 

 found farther north, and this northern species occurs as near as southern 

 Labrador and Anticosti, and ranges across the country to Great Slave 

 Lake. It is, however, separable from it, and whether to be looked on as 

 a distinct species or merely as a variety is a pure matter of individual 

 idiosyncrasy. The question is similar to the preceding, but at present 

 receives no side-light from the west. 



One will hardly fail to notice that while the forest line at the White 

 Mountains is tolerably well marked (at a height of about 4,000 or 4,500 

 feet), it is always succeeded above by a considerable area, where the 

 dwarfed spruce or "scrub," struggling upward with ever diminishing 

 height, conceals the gray rocks in a covering of uniform green, excepting 

 on the unstable surfaces of the steeper slopes, — an area which is strongly 

 contrasted with the barren gray broken rocks above, which lie piled in vast 

 heaps exposed to full view, except where a patch of sedge furnishes a 

 small and barren pasture upon some more favored plateau. The sides of 

 these mountains, where they rise to their highest culmination, are thus 

 divisible into a forest and an alpine region, and the latter into a lower, or 

 scrub, and an upper, or rocky, district ; these two subdivisions of the 

 alpine region correspond fiiirly well with the areas occupied by the two 

 mountain butterflies just mentioned, and I have attempted to represent 

 these areas upon the accompanying map by the two shades of brown, 

 — the darker brown representing the region where Oeneis has its proper 

 home, the lighter where Brenthis most abounds and breeds. There is no 

 doubt that occasional individuals of Oeneis semidea will be found far within 

 the limits of the lower alpine region ; for the fierce blasts of wind wliich 

 sweep around these lofty elevations must sometimes hurl these feeble flut- 

 terers far down toward the wooded valleys, as I have myself seen ; and 

 there is no doubt that they can find their food plant all through the lower 

 alpine region. Nevertheless, the contrast between the occasional and 

 unwilling visitor and the swarms which in their season crowd the upper 

 plateaus is very marked and significant. The localities where I have found 

 them most abundant are the successive sedgy plateaus which flank the 

 upper part of the carriage road on Mt. Washington, and especially the 

 broad area between the sixth and seventh mile-posts, where tlie road takes 

 a side turn, and which I call Semidea Plateau. So, too, one may find an 

 aspiring Brenthis above the limits of the lower alpine region ; but it is very 

 rarely seen there, and the violets on which the caterpillar probably feeds 

 will scarcely ever be found in any abundance within the upper alpine area. 

 It seems fairly deducible from these facts that even the limited area of the 

 barren heights above the White Mountain forests is divisible into two 

 districts, each of which claims a butterfly as its own ; so that in ascending 



