REMARKS ON THE FORM OF THE TOES OF BIRDS.

Although naturalists have laboured, more especially since the time of the great Linnæus, who gave an impulse to the study of natural history unparalleled in that of any other science, to make us acquainted with animals of every class; and although much has been done by them in ornithology in particular, it requires little knowledge to be enabled to say with truth that a great deal more remains to be done. To take an apparently trivial example, let us look to the tips of the toes of birds, and we shall no doubt find much that is curious, and much that has been entirely overlooked. The examination of those parts was suggested to me by the following occurrence.

On the 21st of March 1816, while I was residing at Henderson in Kentucky, great flocks of Golden Plovers happening to be passing from their winter toward their summer haunts, I procured a good number of them. While engaged in drawing a fine specimen, I observed something beneath the claws, which induced me to look more particularly to that part of the toes, when I found there what might be called a second but smaller claw, equally horny with the part properly so called. I examined several others, and, finding them all alike in this respect, I mentioned the circumstance to a friend, who agreed with me in thinking it very curious. Since that period I have generally, on procuring a bird of any kind, looked to its toes, and I have found many species, both of the genus Charadrius and of other Grallæ, similarly supplied with double claws.

Although I use this term, however, let it not be supposed that I consider the parts in question as really subsidiary or secondary claws; for as they are not furnished with a central bone, or process either from the last phalanx or that next to it, they cannot be truly considered as such, however much they may sometimes resemble them.

But, in order to explain to you what I mean, let us take a general view of the subject. If we examine the foot of any common land bird, a domestic fowl for example, we observe that the extremity of its toes under the nail are rounded, and covered with quincuncial papillæ, generally flattened. The extreme degree of this rounded form is seen in the Eagles and Hawks, of which the end of the toe projects beneath the claw, having the appearance of a large round knob or rather pad. It is not, however, my intention at present to describe the structure of this part in the land birds. I may however remark, that in them, as well as in the others, the examination of the parts in question will materially aid in limiting the number of merely nominal species, by disclosing an identity of form, as well as in separating species that have been confounded, by shewing a diversity, as I have had occasion to observe, in several species of both kinds.

In the aquatic tribes numerous remarkable modifications are observed. Beginning with those which have the extremity of the toe largest and most rounded, we find that the Geese, Ducks, and Gulls, supply good examples. Thus in Larus marinus, the protuberance beneath the claw is rounded, and covered with small rounded and flattened papillæ, of which there is a semicircular terminal series of a larger size, as is represented by fig. 1.

FIG. 1.

FIG. 2.

FIG. 3.

The Pelicans and Gannets are similar in this respect to the Gulls, as are the Cormorants, which, however, have the terminal pad projecting and more pointed. In the Guillemots, also, it is rounded, with small distinct rounded scales. In the Frigate Bird, in which the webs are short, and do not modify the pads, the terminal scales are similar to those of the Gulls. In the genus Lestris, they are smaller, and obscured by the webs, their papillæ smaller and more pointed. In the Terns, they are similar to those of the Gulls, but narrower, and with the papillæ large. In Phaeton æthereus, the webs appear to obliterate the terminal papillæ, which are very small. In all these, the extremities of the toes are more or less rounded, and terminated just beneath the claw by a semicircular series of scales larger than those immediately behind.

In the Auks, however, there is a large scale or plate, on the inner side of the middle toe, and then a series of narrow scales. In Mormon glacialis, of which the end of the middle toe is represented by fig. 2, there is a single much recurved narrow horny plate, behind which is a narrow series of oblong scales. In the genus Puffinus, there is also a single short rounded terminal scale or plate.

The Colymbi or Divers have the end of the toe very narrow and flat, with a single small rounded terminal plate, and numerous small scales behind it. These birds have the claws depressed, a form which shews its extreme development in the Grebes. Of the extremity of the middle toe of one of these, Podiceps cristatus, fig. 3. is a representation. Here the claw is almost quite flat, and the end of the toe beneath it is not elevated or rounded as in almost all the other genera, but perfectly depressed, and having its outline concave, but still, as usual, with a series of large scales.

If we now look to the Grallæ, we shall find similar modifications. Fig. 4 represents the lower surface, and the lateral aspect of the extremity of the middle toe of Ardea rufescens, which agrees, in a general point of view, with that of the other species of the genus, as well as with that of the Cranes. The pad here is rounded, and terminated by a semicircle of larger scales. In the genera Numenius and Limosa, the arrangement is similar, the terminal scales being much smaller in the latter than in the former, and two of the lateral scales enlarged. In the genera Tringa, Scolopax and Gallinula, the arrangement is similar. All these genera exhibit more or less of the rounded form, terminated by a series of larger scales.

FIG. 4.

FIG. 5.

FIG. 6.

In Ibis alba the extremity is narrowed and terminated by a small rather pointed horny plate, divided into two unequal portions, as represented by fig. 5. The Tantali have this part also narrowed at the end, flattened, and terminated by a semicircular slightly projecting plate or hooflet. The same appearance is presented in Hæmatopus palliatus, in which, however, the extremity is more rounded, the semicircular plate more decurved, and concave above, as represented by fig. 6. In Rallus elegans, fig. 7, and the Rails generally, the terminal plate is similar, but narrow and rather curved upwards. It is in the genera Strepsilas, Charadrius and Totanus, that the terminal plate, being narrower, more elongated and more pointed, assumes more especially the semblance of a second claw. The extremities of the middle toes of Totanus semipalmatus and Charadrius Pluvialis, are represented by figs 8. and 9.

FIG. 7.

FIG. 8.

FIG. 9.

Having now reached the point from which I started, according to the approved method of reasoning in a circle, or if not, of exhibiting natural objects in a circular arrangement, I take my leave, hoping that when I again request your indulgence, I shall be enabled to present you with something equally curious, and perhaps better calculated to induce you to extend your inquiries into the neglected parts of the structure of those objects, whose investigation cannot fail to raise our minds towards the Being who framed the beautiful and harmonious system of which we form a part.

ERRATA.