ORDER II. PASSERES.
(Perching Birds.)
Though for the most part the birds of this Order are of smaller size than those of the others, yet the immense number of species included in it, which is about equal to that of all others together, renders it the most important of all. It is also considered by naturalists as the most typical; that is, as displaying the properties which distinguish a bird from other animals, developed in the greatest perfection. Great varieties of form and structure are found in a group so immense as this; so that but few positive characters can be assigned which are at the same time common to the whole, and peculiar to them. The power of grasping the branches and twigs of trees with the feet, and the habit of perching upon these, are prominent in the Order; the hind toe is always present, and the claws are not capable of being elevated, as in the birds of prey. The greater number of the species habitually dwell in woods and thickets. The power of flight exists throughout the Order in full perfection, and in some of its genera, as the Swifts and the Humming-birds, may be considered as at its greatest development. The beak varies greatly in form, but its general shape is that of a cone, more or less lengthened. In some of the genera which retain predaceous propensities, a trace of the tooth which marks the upper
