All hummingbirds, as far as I know, lay only two eggs; the young are so tightly packed into the nest, and fit so exactly, that if once taken out it is impossible to replace them. Several springs succeeding my first discovery that these hummingbirds were regular migrants to boreal regions, I watched their arrival. We were quartered for the winter close to the western slopes of the Rocky Mountains. The winters here vary in length, as well as in depth of snow and intensity of cold, 33° below zero being no unfrequent register. But it did not matter whether we had a late or early spring, the hummingbirds did not come until the _Ribes_ opened; and in no single instance did two whole days elapse after the blossoms expanded, but Selasphorus and Calliope arrived to bid them welcome. The males usually preceded the females by four or five days. The Black-throated Hummingbird arrives about a week or ten days after the other two. Marvellous is the instinct that guides and the power that sustains these birds (not larger than a good sized bumblebee) over such an immense tract of country; and even more wonderful still is their arrival, timed so accurately, that the only flower adapted to its wants thus early in the year opens its hoards, ready to supply the wanderer’s necessities after so tedious a migration! It seems to me vastly like design, and Foreseeing Wisdom, that a shrub indigenous and widely distributed should be so fashioned as to produce its blossoms long before its leaves; and that this very plant alone blooms ere the snow has melted off the land, and that too at the exact period when hummingbirds arrive. It cannot be chance, but the work of the Almighty Architect—who shaped them both, whose handiwork we discover at every step, and of whose sublime conceptions we everywhere observe the manifestations in the admirably-balanced system of creation! The specific characters of these three species, whose northern range I believe was first defined by myself, are briefly as follows:— _Selasphorus rufus_ (the Nootka or Red-backed Hummingbird).—Male: tail strong and wedge-shaped; upper parts, lower tail-coverts, and back, cinnamon; throat coppery red, with a well-developed ruff of the same, bordered with a white collar; tail-feathers cinnamon, striped with purplish-brown. Female: plain, cinnamon on the back, replaced with green; traces only of metallic feathers on the throat. Length of male, 3·50; wing, 1·56; tail, 1·31 inches. Habitat: West coast of North America to lat. 53° N., extending its range southward through California, to the Rio Grande. _Stellata Calliope._—Male: back bright-green; wings brownish; neck with a ruff of pinnated magenta-coloured feathers, the lower ones much elongated; abdomen whitish; length, about 2·75 inches. Female, much plainer than the male, with only a trace of the magenta-coloured ruff.