The black guillemot differs from the foolish guillemot (_Uria troile_) only in the colour of its plumage, which, with the exception of a large white patch on the coverts of each wing, is black, silky, and glossy; the feathers appearing to be all unwebbed, like silky filaments or fine hair. The bill, in all the species, is slender, strong, and pointed; the upper mandible bending slightly near the end, and the base covered with soft short feathers. The food of the guillemot consists of fish and other marine products. The _Alcidæ_, or auks, are also included amongst the Arctic birds. The little auk (_Arctica alca_) frequents the countries stretching northwards from our latitudes to the regions of perpetual ice, and is found in the Polar Regions both of the Old World and the New. Here, indeed, they congregate in almost innumerable flocks. At early morn they sally forth to get their breakfast, which consists of different varieties of marine invertebrates, chiefly crustaceans, with which the Arctic waters teem. Then they return to the shore in immense swarms. It would be impossible, says an Arctic voyager, to convey an adequate idea of the numbers of these birds which swarmed around him. The slope on both sides of the valley in which he had pitched his camp rose at an angle of about forty-five degrees to a distance of from 300 to 500 feet, where it met the cliffs, which stood about 700 feet higher. These hill-sides are composed of the loose rocks detached from the cliffs by the action of the frost. The birds crawl among these rocks, winding far in through narrow places, and there deposit their eggs and hatch their young, secure from their great enemy, the Arctic fox. [Illustration: THE AUK.] On one occasion, they were congregated along a slope, fully a mile in length, and over this slope rushed a constant stream of birds, only a few feet above the stones; and, after making in their rapid flight the whole length of the hill, they returned higher in the air, performing over and over again the complete circuit. Occasionally a few hundreds or thousands of them would drop down, as if following some leader; and in an instant the rocks, for a space of several rods, would swarm all over with them, their black backs and pure white breasts speckling the hill very prettily. Though quantities are destroyed by the crews of vessels as well as by the Eskimos, their numbers never seem to decrease. Their flesh is both wholesome and delicate, and affords a welcome change of diet to the mariner weary of salt meat and pemmican. They are very tame, and easily captured,--in some places being actually caught in hand-nets, like moths or butterflies; and they pass a great portion of their time on the ocean, where they disport themselves with equal grace and self-possession.