The Shearwaters are a well-defined group of Petrels, numbering twenty or more species, distinguished by their long, slender bill, long wings, and short tails. As the Fulmars bear a superficial resemblance to the Gulls, so may the Shearwaters be compared with the Auks. Four of these birds are known to visit the British seas and coasts, but only one of them, the Manx Shearwater, _Puffinus anglorum_, is known to breed within our limits, and to occur in any abundance. The upper parts of this Shearwater are black, the lower parts white. The Manx Shearwater is, so far as is known, a resident in the British seas, and widely distributed along our coasts during the season of reproduction. Like its allies, the Petrels, this Shearwater is closely attached to the open sea, living for the most part away from shore, and only frequenting land during its nesting period. Its flight is much more erratic and rapid than that of the small Petrels, or the Gull-like Fulmar, and reminds one more of the Swift. It may be seen dashing impetuously along close above the waves, this way and that, one moment high above the horizon, the next deep down in the trough of the billows, pausing here and there for a moment with rapid beating wings, legs let down, and feet striking the water, to pick up some scrap of food. During the breeding season it is for the most part nocturnal in its habits, but at other times it seems to be abroad both by day and night. That it can swim well and buoyantly, I know from abundant experience, but whether it _dives_, as some writers assert, I am not prepared to say. Some Petrels, however, are habitually known to do so, as, for instance, the species composing the genus _Halodroma_. Shearwaters delight in a rough sea and a brewing storm, every bit as much as the smaller Petrels; no weather seems too boisterous for them. When on our rough night voyage to St. Kilda, we must have passed hundreds of Shearwaters, holding high carnival above the gray waters, flitting round our vessel in weird, erratic flight, like bird ghosts, their gambols in the gloom being most interesting. So far as my experience extends, the food of the Manx Shearwater consists entirely of cuttle-fish and sorrel, but the bird will pick up various scraps thrown from vessels. At St. Kilda this Shearwater is regarded as a delicacy. The natives also obtain quantities of oil from it.