30 
CENTRAL HALL. 
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 nasal horns of the Ehinoceros, shown by sections to 
consist of a solid mass of hair-like epidermic fibres. 
7. The horns of Oxen, Goats and Antelopes, consisting of a 
hollow conical sheath of horn, covering a permanent projection 
of the frontal bone (the horn-core). 
8. The antlers of Deer, solid, bony, generally branched, projec- 
tions, covered during growth with soft vascular hairy skin, and 
shed and renewed annually. 
Against the wall at the back of the bay is placed a case con- 
taining a series of preparations, showing in a very complete 
manner the changes in the dentition of the horse at different 
ages, and above this is arranged a series of antlers of the Common 
Stag or Eed Deer (Cervus elajphus), grown and shed in six suc- 
cessive years, showing the changes which took place in their 
size and form, and the development of the branches or tynes in 
each year. 
The other systems of organs of the class will occupy the 
remainder of the central case of this bay. 
Bay III. Bay No. III. is devoted to the class of Birds. An Albatross 
structure (Biomedea exulans) mounted with the wings expanded, shows 
of Birds. the most important characters by which a bird is externally 
distinguished from other animals. The surface of 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 tlie form of 
a horny beak. A nestling Albatross shows that at this stage of 
its existence the bird is not clothed with true feathers, but only 
with soft down, which serves to keep the body warm, but 
confers no power of flight. An Emu and Apteryx in the lower 
compartment of the case show 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 functionless. In the Penguin, 
the wings are reduced to the condition of fins, and are only 
serviceable for progression through the water. 
In the first wall-case the principal facts in the osteology of the 
