This genus is composed of butterflies which are mainly arctic in their habitat, or dwell upon the summits of lofty mountains, where the summer is but brief. Only a few species are found at comparatively low elevations, and these in British America, or the parts of the United States immediately contiguous to the Canadian line. The most widely known of all the species up to this time is the White Mountain Butterfly, _OEneis semidea_, Say, a colony of which has existed probably ever since the glacial period upon the loftiest summit of Mount Washington, in New Hampshire. A number of species are found in the region of the Rocky Mountains. One species, _OEneis jutta_, Hübner, occurs in Maine, Nova Scotia, and parts adjacent. There are in all about a score of species of this genus recognized by authors as occurring in our fauna. In spite of the fact that these insects are boreal or arctic in their habits, Mr. W.H. Edwards has with marvelous skill and patience succeeded in obtaining the eggs and rearing at his home in Coalburg, West Virginia, a number of species. We are indebted to him for more of our knowledge of the generic characteristics of these insects, in their early stages, than had been ascertained hitherto during a century of investigation. His work is one of the beautiful triumphs of that enduring zeal which is a supreme quality in the naturalist. In their early stages all of the species show a close likeness to one another. (1) =OEneis gigas=, Butler, Plate XXVII, Fig. 1, ♂; Fig. 2, ♀ (The Greater Arctic). _Butterfly._--This, one of the largest species in the genus, occurs on Vancouver's Island. The butterfly hides among the dark mosses and upon the trunks of prostrate trees. The males are vigilant and inquisitive, and dart out suddenly when alarmed, or attracted by passing insects. The females have a slower and more leisurely flight and are more readily taken. Expanse, 2.00-2.25 inches. _Early Stages._--Edwards has figured the egg and the caterpillar in its first three stages, but the remaining life-history of the species awaits investigation. (2) =OEneis iduna=, Edwards, Plate XXVII, Fig. 4, ♂ (The Iduna Butterfly). _Butterfly._--This insect, which even exceeds _OE. gigas_ in size, is found on the Coast Range in northern California. It is decidedly lighter on the outer third of the wings than the preceding species, the male being prevalently a pale yellowish-brown, with the basal and median areas of the fore wing dark brown. On the under side the wings are somewhat lighter than in the preceding species, and the transverse lines are more distinctly marked. Expanse, 2.00-2.30 inches.