expanse of its wings is sometimes not less than 6 ft., yet it weighs only between 3 and 4 lb. Large as is the common heron of Europe, it is exceeded in size by the great blue heron of America (_Ardea herodias_), which generally resembles it in appearance and habits, and both are smaller than the _A. sumatrana_ or _A. typhon_ of India and the Malay Archipelago, while the _A. goliath_, of wide distribution in Africa and Asia, is the largest of all. The purple heron, _A. purpurea_, as a well-known European species having a great range over the Old World, also deserves mention here. The species included in Professor Schlegel's second section inhabit the tropical parts of Africa, Australasia and America. The egrets, forming his third group, require more notice, distinguished as they are by their pure white plumage, and, when in breeding-dress, by the beautiful dorsal tufts of decomposed feathers that ordinarily droop over the tail, and are so highly esteemed as ornaments by Oriental magnates. The largest species is _A. occidentalis_, only known apparently from Florida and Cuba; but one not much less, the great egret (_A. alba_), belongs to the Old World, breeding regularly in south-eastern Europe, and occasionally straying to Britain. A third, _A. egretta_, represents it in America, while much the same may be said of two smaller species, _A. garzetta_, the little egret of English authors, and _A. candidissima_; and a sixth, _A. intermedia_, is common in India, China and Japan, besides occurring in Australia. The group of semi-egrets, containing some nine or ten forms, among which the buff-backed heron (_A. bubulcus_), is the only species that is known to have occurred in Europe, is hardly to be distinguished from the last section except by their plumage being at certain seasons varied in some species with slaty-blue and in others with rufous. The rail-like herons form Professor Schlegel's next section, but it can scarcely be satisfactorily differentiated, and the epithet is misleading, for its members have no rail-like affinities, though the typical species, which inhabits the south of Europe, and occasionally finds its way to England, has long been known as _A. ralloides_.[2] Nearly all these birds are tropical or subtropical. Then there is the somewhat better defined group of little bitterns, containing about a dozen species--the smallest of the whole family. One of them, _A. minuta_, though very local in its distribution, is a native of the greater part of Europe, and has bred in England. It has a close counterpart in the _A. exilis_ of North America, and is represented by three or four forms in other parts of the world, the _A. pusilla_ of Australia especially differing very slightly from it. Ranged by Professor Schlegel with these birds, which are all remarkable for their skulking habits, but more resembling the true herons in their nature, are the common green bittern of America (_A. virescens_) and its very near ally the African _A.