This species, which is nearly allied to the preceding, breeds in the marshes of Central and South-eastern Europe. It is a very scarce and irregular visitor to our eastern and south-eastern shores, especially in spring. In habits it resembles the Black Tern, from which it may be distinguished in summer by its red bill, white tail and tail coverts, and whitish wing coverts. The young may be distinguished from those of _H. nigra_ by their longer toes and much paler rump and tail. Length 9·5 in.; wing 8·25 in. THE WHISKERED TERN Hydrochelidon hybrida (Pallas) This is a more southern species than its congeners, breeding in Spain, on the delta of the Rhone, and eastwards in Turkey, Greece, and South Russia. To our shores it is a very rare visitor, some half-a-dozen specimens only having been obtained. In summer it is not unlike the Black Tern, but it may be recognised by the bill, which is stouter and red; the black of the head and nape is sharply contrasted with the grey of the back. A broad white stripe runs backwards from the base of the bill. Chin and throat grey, shading to black on the belly. In winter the forehead and under parts are white. Length 11·5 in.; wing 9·25 in. THE GULL-BILLED TERN Sterna anglica, Montagu With this species we come to the true Terns or Sea-Swallows, the preceding species being known as Marsh Terns. The Gull-billed Tern is only a very scarce straggler to our shores, being a southern European species though occurring yearly as far north as Denmark. In habits there is nothing to distinguish it from our commoner species. In summer the adult has the whole of the upper parts, including the tail, pearl grey; head and nape dense velvety black; primaries blackish. Under parts pure white; bill and legs black. In winter the head is white streaked with black. Length 15·5 in.; wing 13 in. THE CASPIAN TERN Sterna caspia, Pallas This large Tern is, like the preceding, only a rare straggler to our shores. It nests in Denmark and various islands on the Baltic, as well as in the Mediterranean basin eastwards to the Aralo-Caspian area. Plumage much as in preceding species, but the tail nearly white. Bill vermilion red; legs black. Length 20 in.; wing 16 in. THE SANDWICH TERN Sterna cantiaca, J. F. Gmelin This species arrives on our coasts about the middle of April and at once repairs to its breeding-stations. In England these are very few in number and mostly in the north, but occurring equally on the east and west coasts. In Scotland the colonies are rather more numerous, while Ireland can only boast of one in the north.