CLASSIFICATION OF ANIMAL PREPARATIONS. 433 



In addition to the cuticular appendages above noticed, there 

 are others that, although not strictly belonging to the series 

 of hairs, are, nevertheless, composed like them of a horny- 

 material ; in this list may be included the various kinds of 

 horns, hoofs, scales, quills, and whalebone; aU these will 

 require to be cut into thin transverse and longitudinal sections 

 by the machine ; the darker specimens should be mounted in 

 balsam — the transparent ones, dry ; they all exhibit more or 

 less of a cellular structure, and are objects of great beauty 

 when examined under polarized light : — 



Horn — Antelope, 



— Ibex, 



— Ox, 



— Rhinoceros, African, 



— Indian, 



— Sheep. 

 Hoof— Ass, 



— Camel, 



— Elephant, 



— Horse, 



— Ox, 



Hoof — Rhinoceros, 



— Sheep. 

 Quill — Cassowary, 



— Duck, 



— Eagle, 



— Goose, 



— Turkey. 

 Whalebone — Great whale, 



Piked whale. 



Scales — Pangolin, 



— Turtle. 



Skin. — In order to understand fully the parts which hair 

 and feathers play in the economy of vertebrate animals, it is 

 necessary to become acquainted with the structure termed 

 shin, in which they grow. Their purpose, in the majority of 

 cases, is evidently protective ; in birds, however, many of the 

 feathers, especially those of the wings and tail, are employed 

 in flight, whilst the spines of the porcupine and hedgehog are 

 weapons of defence, and the whiskers of the tiger, cat, and 

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