XXXVi INTRODUCTION. 



are grouped, must be judged of by as many and as constant 

 characters as possible, derived from all parts ; but certain 

 typical characters must be assigned. 



Between 7,000 and 8,000 species of birds have been al- 

 ready described, and when all the true species have been dis- 

 criminated, and the interior of Africa and Australia fully 

 explored, we may expect a considerable increase. A few 

 more may probably be discovered in India, and especiall}- in 

 Burmah, and the countries lying between this and China, 

 but no very numerous additions can be expected from this 

 Continent, nor indeed from America. 



I shall now give a brief account of the Classification of 

 birds into Orders, and the characters on which they are 

 founded. 



When we examine the form of the feet of birds, we are 

 at once struck with the webbed feet of some, to which is 

 generally added a backward position of the legs, and a 

 thick, close-set plumage, impervious to water. Such are the 

 characters of the water birds, the Anseres of Linnasus, the 

 Natatores of Vieillot, Swainson, and Vigors ; and the 

 Palmipedes of Willoughby, Cuvier, and Temminck, an 

 order admitted by all. 



We next find a certain number of birds with, in general, 

 much elongated legs, bare above the knee, and a more 

 or less slender shape. Many of them are found on the 

 sea-shore, on the banks of rivers and lakes, or frequenting 

 marshes or grassy plains. Such are the wading birds, the 

 Grallas of Linnaeus, and Cuvier, the Grallatores of Vieil- 

 lot, Vigors, Swainson, &c. These, however, have" been 

 sub-divided, the Pinnatifides, or Coots, being sepa- 

 rated by some naturalists; and also the Cursores, confined 

 to the Ostriches by certain Ornithologists, but, includ- 

 ing the Bustards and Plovers, according to others. 



