The appearance and disappearance of species within our experience teach us that Nature's lists are not filled once for all, but that the changes which geology shows in past ages continue into the present. Sometimes we can trace the immediate cause, or rather occasion, as in the case of the quail's congeners, the pinnated grouse, and the wild turkey, both of them inhabitants of all parts of the State in the early times. The pinnated grouse has been seen near Boston within the present century, but is now exterminated, I believe, except in Martha's Vineyard. The wild turkey was to be found not long since in Berkshire, but probably it has become extinct there too. Sometimes, for no reason that we can see, certain species forsake their old abodes, as the purple martin, which within the last quarter-century has receded some twenty miles from the seaboard,--or appear where they were before unknown, as the cliff swallow, which was first seen in the neighborhood of the Rocky Mountains, but within about the same space of time has become as common hereabouts as any of the genus. In examples so conspicuous the movement is obvious enough; but in the case of rarer species, for instance, the olive-sided flycatcher, who can tell whether, when first observed, it was new to naturalists merely, or to this part of the country, or to the earth generally? The distinction sometimes made in such cases between accidental influences and the regular course of nature is a superficial one. The regular course of nature is in itself a series of accidental influences; that is, the particular occasion is subservient to a general law with which it does not seem at first sight to have any connection. A severe winter may be sufficient to kill the quails, just as the ancient morass was sufficient to drown the mastodon. But the question is, why these causes began to operate just at these times. We may as well stop with the evident fact, that the unresting circulation is forever going on in the universe. But if the quail, who is here very near his northern limits, has a hard time of it in the winter, and is threatened with such "removal" as we treat the Indians to, his relative, the partridge, our other gallinaceous or hen-like bird, is of a tougher fibre, as you see when you come upon his star-like tracks across the path, eight or nine inches apart, and struck sharp and deep in the snow, or closer together among the bushes, where he stretched up for barberries or buds, and ending on either side with a series of fine parallel cuts, where the sharp-pointed quills struck the snow as he rose,--a picture of vigor and success. He knows how to take care of himself, and to find both food and shelter in the evergreens, when the snow lies fresh upon the ground. There, in some sunny glade among the pines, he will ensconce himself in the thickest branches, and whir off as you come near, sailing down the opening with his body balancing from side to side.