The trachea, when moderately extended, measures 13-1/2 inches in length, inconsiderably depressed, its transverse diameter at the upper part 9-1/2 lines, at the lower 6-1/2 lines; the rings cartilaginous, of moderate breadth, uniform, with a contraction in the middle before and behind, their number 134, the four lowest united. The bronchi are composed of about 20 narrow cartilaginous half rings. The contractor muscles are very broad but thin, their fibres irregularly disposed in front; they become thicker and narrower toward the lower part, and are continued beyond the sterno-tracheal muscles, which come off from the 20th ring from the inferior larynx, to the membrane between the last tracheal and first bronchial ring. BLUE HERON. _ARDEA CŒRULEA_, LINN. PLATE CCCVII. ADULT MALE AND YOUNG. Along with a few other Herons, this is, comparatively speaking, confined within narrow limits along our southern coast in winter. It occurs, however, in most parts of the Floridas, where it is a constant resident, and whence, at the approach of summer, vast multitudes are seen proceeding northward, in search of suitable places in which they may rear their young in security. Many, however, go southward, beyond the limits of the United States, and proceed coastwise to Texas and Mexico to spend the winter, especially the younger birds, when still in that singular white plumage which differs so much from that of the young of every other known species of this genus, except that of the Reddish Egret (_A. rufescens_). At New Orleans, where it arrives at the same period, both from Mexico and the Floridas, its first appearance in spring is about the beginning of March; at which time also multitudes leave the Floridas on their way eastward, to settle in Georgia, the Carolinas, and other States farther east, as far as Long Island in that of New York. Beyond this, I believe, no birds of the species have been met with. They rarely, if ever, proceed far inland, or leave the shores of our large rivers and estuaries. On the Mississippi, the swamps and lakes on the borders of which are so well adapted to the habits of these birds, few individuals are ever seen above Natchez. About the beginning of September, by which time the young are able to shift for themselves, they return southward.