X PREFACE. 



useful introduction to the study of Natural 

 History ; the pursuit of which will be found 

 not only to supply inexhaustible sources of 

 intellectual gratification, but also to furnish, to 

 contemplative minds, a rich fountain of re- 

 ligious instruction. To render these benefits 

 generally accessible, I have confined myself to 

 such subjects as are adapted to every class of 

 readers ; and, avoiding all unnecessary ex- 

 tension of the field of inquiry, have wholly 

 abstained from entering into historical ac- 

 counts of the progress of discovery ; content- 

 ing myself with an exposition of the present 

 state of the science. I have also scrupulously 

 refrained from treading in the paths, which 

 have been prescribed to the other authors of 

 these treatises ; and have accordingly omitted 

 all consideration of the hand, the voice, the 

 chemical theory of digestion, the habits and 

 instincts of animals, and the structures of 

 antediluvian races ; the extent of the field 

 which remained, and which, with these few 

 exceptions, embraces nearly the whole of the 

 physiology of the two kingdoms of nature, 



