together that there is barely room for each to feed. At the moment of writing this, we can see from our study-window seven out of a flock of a score feeding so closely crowded as to have their fleeces in actual contact. And yet the field is by no means small, and other parts of it have grass equal in goodness to the corner where these seven sheep are nibbling it to the very root, while the rest of their companions are only at a few feet distance, in the same quarter of the field.

In order to arrive at the cause of this sociality, which seems not only to be without any reasonable motive arising from mutual advantage, but to be rather disadvantageous from the pasture being exhausted by the crowd of feeders, we must consider these sheep as domesticated, and, of course, in different circumstances from the species in their original state of wildness and freedom, in which such sociality may serve some important purpose. The sheep of mountainous countries, where they are in a state of comparative wildness, though unconfined by fences, like those in the meadow just alluded to, are observed to keep together in bands, and to pass from one mountain platform to another in regular ranks, one deep, always headed by a leader. The duty of this leader is to give warning of the approach of danger to his troop, both when on a march of removal to a different pasture and also while they are feeding. This fact, which has often been recorded, we have had more than once an opportunity of witnessing in Wales. On as

cending Snowdon, for example, our attention was attracted by the deep harsh krroup of a raven sailing about on the air, looking out, no doubt, for some luckless sheep enfeebled by accident or disease upon which he might pounce. Immediately from the shoulder of the mountain above us the note of

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the raven was answered by the alarm-call of the leader of a small flock of sheep who were feeding on the scanty herbage of this lofty region; and, at the signal, they quickly drew closer together, and, forming a serried phalanx," eyed their enemy with a bolder bearing than we could have deemed possible in animals proverbial for timidity. The raven was not long in discovering that he had little chance of singling a victim from so watchful and wary a band, and flew off towards the neighbouring cliffs, where he might chance to light upon the carcass of one left undevoured by some fox scared from his prey, or accidentally precipitated, as we have seen happen, from the rocks above. On the departure of their enemy, the sheep began to feed again, but warily at first, raising their heads at intervals to assure themselves that he was really gone; while, to render assurance doubly sure, their leader again took his station as sentinel for the common weal*.

Now we are disposed to conclude, that these two cases of the sheep and the raven may, so far as food is concerned, be taken as the general conditions of the solitary and gregarious habits of birds. One whose food is confined to living prey will prowl alone, because along with associates he might fare scantily; while those who feed on seeds and other vegetable substances, easily obtained in abundance, congregate that they may feed more safely, by appointing, as the mountain sheep do, a sentinel to warn them of danger. The raven, indeed, can hardly be looked upon as subsisting wholly on living prey. It is not furnished by nature with sufficiently formidable weapons for this purpose; and almost uniformly when carrion cannot be obtained, it attacks lambs, sickly sheep, or such as have fallen into a ditch or bog, * J. R.

are seen more eagerly hawking for flies, and ducks carefully trimming their feathers, and tossing up water over their backs, to try whether it will run off again without wetting them. But it would be as absurd to accuse the swallows and ducks on that account of being the cause of rain, as to impute a tempest to the spiteful malice of the poor petrels. Seamen ought rather to be thankful to them for the warning which their delicate feelings of aërial change enable them to give of an approaching hurricane.

"As well," says Wilson, " might they curse the midnight light-house that, star-like, guides them on their watery way; or the buoy that warns them of the sunken rocks below, as this harmless wanderer, whose manner informs them of the approach of the storm, and thereby enables them to prepare for it." The petrels are nocturnal birds. When, therefore, they are seen flying about and feeding by day, the fact appears to indicate that they have been driven from their usual quarters by a storm; and hence, perhaps, arose the association of the bird with the tempest. Though the petrels venture to wing their way over the wide ocean as fearlessly as our swallows do over a mill-pond, they are not, therefore, the less sensible to danger; and, as if feelingly aware of their own weakness, they make all haste to the nearest shelter. When they cannot then find an island or a rock to shield them from the blast, they fly towards the first ship they can descry, crowd into her wake, and even close under the stern, heedless, it would appear, of the rushing surge, so that they can keep the vessel between them and the unbroken sweep of the wind. It is not to be wondered at, in such cases, that their low wailing note of weet, weet, should add something supernatural to the roar of the waves and whistling of the wind, and infuse an ominous dread into minds prone to superstition.

provision of nature; as otherwise, the putrefaction caused by the constant and excessive heat would render the air insupportable to human life. These birds are familiar in Carthagena; the tops of the houses are covered with them: it is they who cleanse the city of all its animal impurities. There are few

rida, where they abound. Forster says they bury themselves by thousands in holes under ground, where they rear their young and lodge at night; and at New Zealand, the shores resound with the noise, similar to the clucking of hens, or the croaking of frogs (Pontoppidan, speaking of those of Norway, says like the neighing of a horse), which they send forth from their concealment.

"As the stormy petrel," says Mr. Drosier, "is scarcely ever to be seen near the land, except in very boisterous weather, one of the natives (of Foula), for a trifling remuneration, agreed to traverse the face of a rock, and take me some from out its fissures. Accordingly, accoutred with a rope of hemp and hog'sbristles coiled over his shoulders, he proceeded to the cliff. Having made one end fast by means of a stake, he threw the coil over the face of the rock, and gradually lowered himself down, but with the utmost caution and circumspection, carefully pressing his foot hard upon the narrow ridges before he at all loosened his firm grasp of the rope, which he never altogether abandoned. I had previously thrown myself upon my chest, to enable me to have a better view of him, by looking over the cliff; and, certainly, to see the dexterity and bravery with which he threw himself from one aperture to another, was truly grand. The tumbling roar of the Atlantic was foaming many hundreds of feet beneath, and dashing its curling cream-like surge against the dark base of the cliff, in sheets of the most beautiful white; while the herring and black-backed gulls, alternately sweeping past him so as to be almost in reach of his arm, threw a wildness into the scene, by the discordant scream of the former, and the laughing, oft-repeated bark of the latter. This, however, he appeared entirely to disregard; and, continuing his search, returned in about half an