It is common to say that these occasional winter Swallows are the later broods of young, which, being too infantile to migrate, are compelled to linger in the country of their nativity, and becoming lethargic from the advancing cold, at length die before the spring. But when this hypothesis is looked at, it seems hardly tenable. In many of the instances recorded, the specimens seen even late into the winter, are represented as gaily and vigorously hawking for flies, or sweeping over the water as in summer. This does not look like poor deserted orphans starved with the cold, retiring to die; but birds in health, temporarily awakened from normal slumber by an unusual temperature, and instantly ready for a full use of their faculties. However, to settle the point by fact, Mr Bell distinctly states that his specimen of December 10th was "an adult bird, not a young bird of the season."
If it should be asked why they do not appear in January or February, as well as November and December, the answer is obvious. The winter's lethargy of hybernating warm-blooded vertebrates is much more readily interrupted in the earlier part of the season than in the middle and latter part. And this is natural; for the more intense cold of January benumbs and suspends the vital functions far more completely, and the coma so superinduced is sufficiently deep to resist the counteracting influence of a few warm days, even though the temperature should be as high as on those earlier days that awakened them, or even higher.
The aggregate evidence, then, seems to leave no room for reasonable doubt, that a certain number of our Hirundinidæ,—few, indeed, as compared with the vast migrant population, but still considerable, looked at per se,—for some reason or other, evade the task of a southward flight, and remain, becoming torpid, occasionally betrayed into a temporary activity, and resuming their active life, about the same time, or occasionally a little before the time, of the arrival of their congeners from abroad. It is, however, desirable for the absolute settlement of the question, that specimens, actually discovered in a lethargic condition, should come under the observation of competent scientific naturalists, open to conviction, who would leave them in situ, keeping an eye on them from time to time till the return of warm weather in spring. It is not enough to take them into a warm room, and to shew that they revive in such circumstances: we want to know positively whether they will be resuscitated normally and naturally by the vernal warmth, and come forth spontaneously to sport, and wheel, and skim, and soar, and stoop, and hawk, and twitter,—among their travelled fellows. Who will undertake to decide the point in this manner? He will have achieved a name in science.
VI.
THE CRESTED AND WATTLED SNAKE.
About the middle of the last century there existed in Amsterdam a Museum of natural history, which, though accumulated by the zeal and industry of a private individual, far exceeded in extent and magnificence any collection then in the world. It had been gathered by Albert Seba, a wealthy apothecary in the Dutch East India Company's service, who fortunately published an elaborate description of its contents. This great work, "Locupletissimi Rerum Naturalium Thesauri accurata Descriptio,"—in four volumes folio, published from 1734 to 1765,—is even now remarkable for the accuracy and beauty of its copious engravings, which still are referred to as authorities, though the descriptions are devoid of scientific value. Many of these figures and descriptions, about whose reality no shadow of doubt exists, are those of creatures which are altogether unknown to modern science, and some of them are highly curious.
Serpents seem to have been a special hobby of Seba's; and he has delineated a vast number of species. Among them are two[141] about which a singular interest hangs. They are of rather small size; the one pale yellow, marked with oval reddish spots, the other reddish, with five green transverse bands. The head in each case has a horny-pointed muzzle, and the cheeks are furnished with depending wattles of a coral-red hue.
From the expressions of wonder with which Seba introduces his descriptions of these animals, it is evident that they were no ordinary forms. He does not know whether to call them Eels or Serpents, the critical characters, which in our day would instantly determine this point, being then scarcely heeded. He calls them "marine," but whether on any other evidence than the pendent processes of the cheeks, which he calls "fins," does not appear. But no fish known to naturalists will answer to these representations. The pointed head, indeed, resembles in some respects that of Murœna, but this genus of fishes is altogether destitute of pectoral fins, while the vertically-flattened tail, and the long dorsal and anal fins confluent around the extremity of the body in Murœna, are totally unlike these figures. These and all similar fishes are, moreover, destitute of visible scales; but in these the scaling is decidedly serpentine, and the second, in particular, has large symmetrical plates across the belly, while the head in both is shielded with broad plates like a Colubrine Snake. The tail is drawn out to a long conical point, without the slightest appearance of compression or of bordering fins. In one figure there is seen a little projecting point at the edge of the lower belly, which at first sight suggests the idea of the anal hook of a Boa, but which, by comparison with other figures, we discover to be intended to represent the projection of the pre-anal scale. The very minuteness of this character makes it valuable: its value was doubtless unheeded by the artist, who merely drew what he saw; it is, however, a very decisive mark of distinction between a serpent and a fish.