PLUMAGE OF BIRDS.

As in the popular study of birds, reference is most frequently made to the plumage, as distinctive of the several species, we have thought it well to explain somewhat fully its nature and construction: and this we cannot do more lucidly and concisely than in the words of MUDIE,* who illustrates his subject with the following cut of the Garrulous Roller (Coriacius garrula); because, although rare as a British bird, it is one in which the different feathers are very distinctly marked, and the parts well defined. The upper surface is here only represented; but as the back is the most interesting part, and the one most usually noticed, this will be sufficient for our present purpose.

1. Is the ear covert, which consists of certain soft feathers, which cover the external organ of hearing. They vary considerably in birds of different species, and on that account they are of considerable use as means of distinction.

2. The scapulars, or feathers, which cover the shoulders and shoulder-bones, and the places where the humeri, or first bones of the wing, answering to the bones of the human arm above the elbow, are articulated. They unite, without much distinction, with the common feathers of the back, and along with those of the wings and the sides. The scapular feathers serve only as clothing to the parts which they cover, but they form a thick, and comparatively a downy covering, which, while it admits of easy motion, preserves the important joints which it covers from the varieties of the weather.

3. The bastard wing.-This consists of a greater or smaller number of feathers, bearing some resemblance to the quills of the true wing. They grow from a little bone, which is united to the third or wrist joint of the wing; and they, and the bones by which they are supported, are generally strong in proportion to the power of flight in the bird. Indeed, there is generally a development of all that part of the wing which corresponds to the hand, proportional to the power of flying. Thus, in the wing of the Jer Falcon, which may be considered as the bird of finest and most graceful flight, the thumb consists of two distinct bones, and even a marking, as if the last two were united; and the four fingers may be traced, the first in a long bone, the second in a small one, and the third and fourth in two ribs, united by a very. thin plate of bone. The use of the bastard wing is not very well known, because the action of the different parts of the wing, during flight, is not easily observed; but it is probable that it prevents the wing from turning upwards, and even gives the point of it a downward motion, in the contrary direction to that in which the wing is moved, and thus propels it forward.

4. The lesser wing-coverts.-These are the first parts of the plumage of the wings, which in all birds take the form of definite and firm feathers. There are generally several rows of them; and there are under-coverts, which answer to them, and line the under or inner side of the wings, but these are more slender and downy in their consistence, and, generally speaking, they have less colour.

5. The greater wing-coverts.-These lie under the lesser ones, and are still larger and stronger, stretching a considerable way over the quills or flying feathers, and being supports to these for a greater part of their length than the lesser coverts. They are also much stronger, in proportion to the coverts which answer to them on the under-sides of the wings.

6. The primaries, or principal quills. These form the termi. nation of the wings, and are the strongest feathers on the bird. They rise from the hand, or that portion of the wings which is below the wrist joint, and which, though it sometimes contains three distinct bones in its length, is frequently called the first (or third) bone of the wing. These feathers are numbered in order; the outer one, or that which is foremost in the expanded, or lowest in the closed wing, is the first. Considerable differences in the form of wings arise from the various lengths of the feathers; and these are accompanied by corresponding variations in the style of flight. If the first or second of these feathers be the longest in the wing, (and when the second is longest the first comes underneath and supports it,) the bird can turn in the air with greater ease than with any other form of wing. Birds which hawk flying, or catch their prey while on the wing, whether they catch other birds, as the Falcons, or insects as the Swallows, have their wings of this construction. The Pigeons, which are also birds of excellent wing, have the second feather longest; but the Lapwing, which is remarkable for the variety of its motions in the air, has the longest feathers far into the wings.

7. The secondaries, or second quills of the wing. They arise from that part of the wing which is commonly called the second bone, and which answers to the fore-arm in man. They come from it towards the wrist joint, and admit of a folding of the wing between them and the primaries, when the wing is closed. When the wing is open they sometimes appear a continuation of the same curve with the primaries, and at other times they form a distinct curve of their own.

8. The tertiaries, or third quills of the wing. They arise chiefly from the same bones as the secondaries, but nearer to the elbow joint. In some birds, especially those which are in the habit of running very swiftly with the wings partially opened, the ter tiaries are often so long, and come so to a point, that the bird appears as if it had four wings, or rather had a double wing on each side. This form of wing answers some important purposes in their economy.

From the manner in which the several coverts support each other and the quills, the wing is a finer combination of lightness, strength, elasticity, and stiffness, than could be produced by any other means. These coverts support, and admit of motion upon each other, not unlike that which takes place in a coach-spring, which is about the best of our mechanical contrivances for rendering motion smooth and free from jolts, at the same time that the compound spring is much less liable to be broken than if it were formed of a single piece of metal.

9. The rump-feathers and upper tail-coverts. The first of

these are a continuation of the covering of the back; and the second support the tail feathers on the upper side, and are strong in proportion, as these are adapted for action in flying. In birds which use the tail as the means of support in fixing themselves upon upright surfaces, as is the case in the Woodpeckers, the upper tail coverts are very strong and close, and so thick is their array, as to give that organ the same stiffness as a powerful wing. In those birds, also, which have to take wing from the water, and yet have not the feet webbed and placed far backwards, so as to support them when rising, the tail-coverts are peculiarly strong, in order to support the tail feathers, which are the principal fulcra from which the bird gets into the air.

10. The vent feathers and under tail-coverts, which cover the hinder part of the bird; and in those birds in which the tail feathers are long and stiff, and much used in the act of flying, support the under side of these feathers, in the same manner as the under-coverts support the quills of the wings. In those birds which have a habit of flirting up the tail, the under-coverts are longer and stronger than in those which have no such habit.

The tail feathers require no reference. They vary much in their numbers and length, and also in the form of their terminations, and the motions which the bird can communicate to them. In some birds the whole, or, at least, great part, of these feathers appear to be merely ornamental, which of course means nothing more than that their uses have not been observed. In general, however, they act both as a rudder in flying, and as a means of directing the motion upwards or downwards. Analogy would indeed lead us to suppose that their chief use is in the upward and downward motion, because their greatest surface is generally horizontal. The analogy is further confirmed by the fact, that many of the low-flying birds have the breadth of the closed tail in the vertical plane, though these also can, in general, spread it out like a fan when they fly.

The other feathers are to be considered rather as the clothing of the bird than as active instruments in its flight, or as auxiliaries in its motions upon the land or the water. But still they are not less worthy of notice, both in the distinguishing of one bird from another, and in tracing how well all the parts of birds are adapted to their general habits and their haunts. These ordinary feathers are imbricated-that is, they are placed one over the edges of two-as slates or tiles are in a covering of a roof. By means of this arrangement, all the parts of the bird are equally feathered, and so they are equally proof to the action of the atmosphere. The lines in which the several rows of feathers are placed, form very curious curves, and their shafts diverge or

converge so naturally, and with so perfect agreement, to the sur face which they cover, that no line of separation can be traced.

The feathers of birds, the coverings of the featherless parts, and even the beaks and claws, are all, chemically speaking, formed of nearly the same materials; and nearly the same with the hair and cuticle of all animals, and even with the epidermis which covers living shells. This material is coagulated albumen, or nearly the same substance as white of egg when consolidated by heat, in which state it better resists the action of water than almost any other flexible substance. This substance is, especially in the upper or more coloured and glossy part of the feathers, combined with oils and metallic substances in very minute portions; but in the down and the light-coloured feathers it is nearly

pure.

The under part of the clothing feathers, and also a small por tion of almost all feathers near the tube or barrel, consists of down, but the exposed surfaces, even of the softest feathers, are smoothed so as to throw off the water. This is the case even in those water-birds which pass the greater part of their time with the under part of the body immersed in water. On them, the down is abundant in proportion as the habits of the birds expose them to cold; and the external surface is waterproof, from its glossy texture, and (possibly ?) also from the oil with which the bird anoints it by means of its bill: but in all birds there is an external surface, adapted to prevent decomposition, and an inner downy matter, as a protection against changes of temperature. The down is partly on the root-ends of the feathers, and partly on the skin in the intervals between them, but the material is in all cases substantially the same; the difference is in the form, or in the colour, which generally approaches nearer to white in the down than in the feathers. When the bird remains all the year round in situations where there are great differences in the heat of the seasons, the down increases in quantity during winter; and when birds of a warmer climate are domesticated in a colder one, they become more downy. The form which the down assumes is often characteristic of the habits of the bird. In the Ostrich there is none; in some birds it is a mere tuft at the origin of the webs, in others it is a second feather originating there; and there are all the intermediate states in different birds, and very considerable seasonal differences in the same bird.

Different birds find their food in different states, both of the atmosphere and the waters; and very beautiful corresponding differences in their plumage may be traced. The plumage upon the Raven, which braves the storm in the wilds, is very different from that of the gallinaceous or poultry races, which a slight shower drives to their cover or their perch; and Ducks and other