48 SYSTEMATIC ARRANGEMENT. 



and in this work out of place ; so we shall chiefly fol- 

 low that of Cuvier, though with some slight varia- 

 tions. The necessity which Cuvier, who had studied 

 the structure of animals intimately, and endeavoured 

 to arrange them according to it, found himself under 

 of sometimes using the bills, sometimes the feet, and 

 sometimes the wings, as the leading characters of his 

 subdivisions, shows very forcibly the difficulty which 

 attends this class of animals. 



But before any system can be made intelligible to 

 those who do not already understand the subject, we 

 must give some explanation of the structures and 

 functions on which the systematic arrangement is 

 founded ; and this will be rendered more easy of 

 consultation by markinj it off into portions under 

 separate titles. 



