5. The special epidermal appendages found in nearly all Mammals on the ends of the fingers and toes, called according to the various forms they assume, nails, claws, or hoofs. 6. The one or two unpaired horns of the Rhinoceroses, shown by sections to consist of a solid mass of hair-like epidermic fibres. 7. The horns of Oxen, Goats, and Antelopes, each consisting of a hollow conical sheath of horn, covering a permanent projection of the frontal bone (the horn-core). 8. The antlers of Deer, forming solid, bony, and generally branched projections, covered during growth with soft hairy skin, and in most cases shed and renewed annually. On the wall is arranged a series of antlers of an individual Stag or Red Deer (_Cervus elaphus_), grown and shed (except the last) in thirteen successive years, showing the changes which took place in their size and form, and the development of the branches, or tines, in each year. In old age the number of these tines tends to diminish. On the north side of the table-case are shown dissections of the principal internal organs of Mammals. [Sidenote: Bay III. General structure of Birds.] Bay No. III is devoted to the class of Birds. An Albatross (_Diomedea exulans_) mounted with the wings expanded shows the most important characters by which a Bird is externally distinguished from other animals. The body is clothed with feathers, which (in the majority of Birds), by their great size and special arrangement upon the fore-limbs, enable these to act as organs of flight. The mouth is in the form of a horny beak. A nestling Albatross shows that at this stage of its existence the bird is not clothed with ordinary feathers, but with soft down, which serves to keep the body warm, although it confers no power of flight. An Emu and an Apteryx in the lower compartment of the case display the exceptional condition (found only in a comparatively few members of the class) of Birds with wings so small as to be concealed beneath the general feathery covering of the body, and quite useless. In the Penguins, of which two species are shown in the case, the wings are reduced to the condition of fins, and are serviceable only for progress through water. In the first wall-case the principal features of the skeleton of the class are shown. Sections of bones exhibit the large air-cavities within; a complete skeleton of an Eagle, with the bones separated and named, and mounted skeletons of the Ostrich, Penguin, Pelican, Vulture, Night-Parrot, Fowl, etc., show the chief modifications of the skeleton. The Apteryx possesses the smallest, and the Frigate-bird the longest bones of the wing, the correspondence of which can be readily traced by means of the labels attached to them. The under surfaces of the skulls of various birds are shown with the different bones coloured to indicate their limits and relations; these are followed by a series of the different types of sternum or breast-bone.