The spring migration is confined to birds that pass the winter in the South, in many cases not beyond the limits of the United States; but there are birds that extend their journey to the islands of the West Indies, to Mexico, and to Central America, and in some instances to South America. Many of the Warblers, several of our common Thrushes and Finches, and various others of our well-known North American species, visit Cuba and Jamaica in the course of the winter, and in both those islands some of them make their appearance while yet the season is not so far advanced in the United States as to incommode them either by the cold or an abridged supply of their favorite food. The migration of these birds is a curious problem, and regulated by laws entirely independent of the considerations of climate and supply of food. One cannot readily find a reason why a bird that has passed the winter in a tropical or southern latitude, should leave for the North at the coming of spring, when a more plentiful supply of food than has sufficed for its winter support is about to be presented. And then, too, why should birds proceed so far to the North?—to the very confines of the Arctic circle, as many small species do, when the great forests of the middle and northern States offer ample accommodation, and supplies of food certainly equal to those in which they will at last terminate their journey. There are questions here difficult to answer. It would appear that the existence of an animal is predicated on its performance of certain functions antecedently involved in its organization. That its entire history, we may say, is but an answer to the calls of organization. That the organization and the performance of its indicated functions are strictly exponents of each other, the latter modified by circumstances, and the relations of species to each other, dependent in some measure on circumstances, but not produced by them, no more than forms or other physical characters. No feature in the history of an animal is absolutely produced by circumstances. There is, too, the consideration of inherited instincts, and if the faculty of memory, and impressions on it, are transmissible, nearly the whole phenomena of instinct may be explained. In the western and southwestern countries of North America, within the limits of the United States, various species of northern birds appear in winter that have never been noticed on the Atlantic seaboard. The handsome little bird that we present to the reader in the plate now before him, is one of that description. It appears to be a native of the extensive and little-known regions of northwestern America, migrating in the winter to California, New Mexico, and Texas, where it has been seen by several of our naturalists.