[Illustration: FIG. 16.--EGG OF THE GREAT AUK OR GARE-FOWL: Size of nature.] [Sidenote: Groups of British Birds and Nests.] Down the middle line of the gallery, as well as in many of the bays, are placed groups showing the nesting-habits of various species of British birds. The great value of these groups consists in their absolute truthfulness to nature. The surroundings are not selected by chance or from imagination, but in every case are carefully executed reproductions of those that were present round the individual nest. When it has been possible, the actual rocks, trees, or grass, have been preserved, but in cases where these could not be used, they have been accurately modelled from nature. Great care has also been taken in preserving the natural form and characteristic attitudes of the Birds themselves. Among the more attractive cases are, near the centre of the gallery, a pair of Puffins feeding their single young one, and Black-throated Divers with their eggs in a hollow in the grass on the edge of a mountain-loch in Sutherland. Hen-harriers--the male grey and the female brown--are shown with their nest among the heather from the moorland of the same county. On the left of these is a Peregrine Falcon’s eyrie, on the ledge of a rocky cliff, containing three white downy nestlings. Near by are various species of Ducks, notably the Red-headed Pochard on the sedgy border of a Norfolk mere. In the last bay but one on the right side is a nest of the Heron, in a fir-tree, with the two old birds and three nearly fledged young. Various species of Gulls and a particularly beautiful group of Arctic Terns from the Shetland Islands are exhibited in the middle line towards the west end of the gallery and in the eighth and ninth bays. In the eighth bay on the right side and in the adjoining passage are Plovers, Sandpipers, Snipes, etc., some of which (especially the Ringed and Kentish Plovers) show the wonderful adaptation of the colouring of the eggs and young birds to their natural surroundings for the purpose of concealment. In the second passage leading to the Coral-gallery are Ptarmigan and Capercaillie from Scotland, and in the adjacent part of the middle line Wood-Pigeons and Turtle-Doves building their simple, flat nests of sticks in ivy-clad trees. In the fourth, sixth and seventh bays on the left are Sand-Martins and Kingfishers, showing, by means of sections of the banks of sand or earth, the form and depth of the hole in which the eggs are placed; and also nests of the Swift, Swallow, and House-Martin, all in portions of human habitations. [Sidenote: Pavilion, with British Land and Fresh-water Vertebrates.[9]]