This species is in weight about four pounds; the bill is dusky, and about four inches in length; a bare yellow skin is situated along the sides of the mouth and chin, the latter speckled with black. The whole bird appears black at a little distance, but on nearer examination, the head, neck, breast, and rump are of a glossy green. The feathers of the upper part of the back, scapulars, and wing coverts are pointed, and beautifully glossed with purple, violet, and green, each feather being edged with a velvety black; the under part of the body is less glossed with green; the legs are dusky black; middle claw serrated. The female weighs over three pounds; the upper part of her body is dark, not so densely glossed as in the male; but the margin of the feathers of the scapulars and wing coverts is black, the under part dusky, with a mixture of grey. Such is Colonel Montagu's description of a pair shot from the nest, but they vary in plumage and colour. In habit the Shag is strictly a salt-water bird, never visiting fresh water, breeding on our rocky coasts, where it builds a nest of stick and sea-weed. They resort to the maritime caves of the Hebrides in such vast numbers that they literally cover the sea to a considerable extent when on their passage from the caves of Liuir and Toehead to their fishing-grounds in the sound. Mr. McGillivray has counted a hundred and five in one flock. This picture Mr. McGillivray makes the text for one of his most delightful descriptions:-- "There is a large cave," he says, "on the west coast of Harris, celebrated for the number of Shags which reside on it, and so lofty that a boat can enter it to a considerable distance with lowering the masts. When we appear off the mouth of the cave a considerable number appear conspicuously perched on the little shelving rocks and projections, their dusky figures strongly relieved by the whitened surface of the rocks. Some of them fly overhead as we approach, but more drop into the water like a stone. On looking down we see them rapidly winding their way under the boat, swimming with outspread wings, and not at all in the manner represented by some writers, who say that it propels itself entirely under water by the feet and tail. Glancing aloft, we see many Black Guillemots in the clefts; and above them is the eyrie of the White-tailed Eagle. But our business is with the Shags, which are now seen writhing their long necks as they gaze upon us. Presently a shot is fired, and another; the dead birds drop on the water, the living plunge headlong into it, many advance on the wing, but, being frightened by the upraised oars, dart into the water.