From Aristotle or Pliny little can be gleaned of the history of these birds. Aristotle states that the Gaviæ and Mergi lay two or three eggs on the rock--the Gaviæ in summer, the Mergi in the beginning of spring--hatching the eggs, but not building in the manner of other birds. Pliny says that the Gaviæ build on rocks, the Mergi sometimes on trees; from which remark it appears probable that the genus _Mergus_ then included not merely the various divers, but also the cormorants, as was formerly conjectured by Turner. Whilst, therefore, the ancient Latin name of gull, _Gavia_, has been entirely removed from modern nomenclature, the word Mergus has obtained a signification very limited in comparison to that which it enjoyed among the ancients, being now applied to the Mergansers alone, although for a time restored by Brisson to the Colymbi, which, as possessing the property of diving in its highest perfection, seem most entitled to retain it, whilst the term _Merganser_ might be judiciously applied to the genus now called by some, _Mergus_, as was done by Aldrovandus, Willoughby, Brisson, and Stephens. The remarkable differences in the habits of gulls, which form in part the basis of separation, as suggested by Boië in the case of the blackheaded gulls, were early noticed. Old Gesner (1587) says that some gulls dwell about fresh waters, others about the sea; and from Aristotle, that the grey gull seeks lakes and rivers, whilst the white gull inhabits the sea. Every one indeed must have noticed the flocks of gulls which occasionally appear inland, and share with the rooks and other corvidæ the rich repast of grubs which is afforded by the fresh-ploughed land. The common gull (_Larus canus_) is one of those which indulge in these terrestrial excursions; but the blackheaded gulls (_Xema_) select even the inland marshes as their breeding-places. The more truly maritime gulls select islands or rocks, on the surface of which they deposit their eggs, as the kittiwake the narrow ledges of precipitous cliffs, the young being reared with safety, where it would seem that the least movement must plunge them from the giddy height into the abyss below. This beautiful illustration of the power of instinct to preserve even the nestling from danger, is admirably displayed on the northern coast of Mayo, where at Downpatrick Head the whole face of the perpendicular limestone cliff is peopled by line above line of gulls, flying, when disturbed by a stone thrown either from mischievous or curious hand, in screaming flocks from their eggs or young, and as quickly settling upon them again, without, as it were, disturbing the equilibrium of either in a place where to move would be to tumble into destruction. The clamour of the kittiwake is indeed so great on such occasions that it has given rise in the Feroe Islands to a proverb, “noisy as the Rita in the rocks.” The eggs of several species of gulls are used as food, being regularly sought for as such on the coast