26 
CENTRAL HALL. 
cast of a section of the tail of a great extinct species (Glyptodon) 
shows well a bony external as well as internal skeleton. 
3. The outer covering modified into true scales, much resem- 
bling in structure the nails of the human hand. This occurs 
in only one family of mammals, the Pangolins or 3fanidce. 
4. Hair in various forms, including bristles and spines. A 
stuffed specimen of a Porcupine at the bottom of the case 
affords a good illustration of a spiny covering. The two 
kinds of hair composing the external clothing of most mam- 
mals, the long, stiffer outer hair, and the short, soft under 
fur, are shown by various examples. 
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 PJiinoceros, 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. 
On the wall at the back of the bay is placed a series of 
antlers of the Common Stag or Eed Deer (Cervus elapJms), grown 
and shed in six successive 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 this bay. 
Bay III. Bay ISTo. III. is devoted to the class of Birds. In the first 
rtmcture wall-case the principal facts in the osteology of the class are 
of Birds. 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, Fowl, &c., show the chief modifications of the skeleton. 
The Apteryx shows the smallest, and the Frigate bird the largest 
Ijones 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 
