18 
CENTRAL HALL. 
2. The development of bony plates in the skin, found among 
mammals only in the Armadillos and their allies. The cast 
of a section of the tail of a gigantic extinct species 
{Glyptodon) shows a bony external as well as internal skeleton. 
3. The outer covering modified into true scales, much resem- 
blinc^ in structure the nails of the human hand. This occurs 
in only one family of mammals, the Pangolins, or Manidce. 
4. Hair in various forms, including bristles and spines. The 
two kinds of hair composing the external clothing of most 
Fig. 2. — Flying Lemur. 
mammals, 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. 
G. Tlie nasal and frontal horns of the Ehinoceroses, shown by 
sections to consist of a solid mass of hair-like epidermic fibres. 
7. 'J'he horns of Oxen, Goats, and Antelopes, consisting of a 
hollow conical sheath of liorn, covering a permanent projection 
of LIk; fVont;il borui (tli(; li()n)-(;ore). 
