16 INTRODUCTION. 
In the Accipitres, represented by the Eagles and 
Falcons, the wings are long and powerful, and their 
food consisting mostly of the flesh of small animals, 
they are not only assisted in their pursuit of them 
by a rapid and vigorous flight, but the form of the 
feet and claws is such as to enable them to seize and 
secure their prey, while the hooked beak is well 
suited to the purpose of tearing it in pieces. 
The Insessores embraces a great variety of birds 
exhibiting a corresponding variety of form. A large 
majority of them feed upon insects and their larvee 
or eggs; and while in all, the feet are well adapted 
for perching, the bill and wings will be found to vary 
much according to the habits of the bird. The 
Swallows, Fly-catchers, Tyrants, etc., pursue their 
food upon the wing ; they have therefore great powers 
of flight, the mouth is wide, the bill broad at the 
base, and sometimes armed at the extremity with a 
slight hook. The Warblers, Thrushes, Wrens, and 
many others, seek their food among the branches and 
leaves of the trees, feeding mostly upon the worms, 
and Oscines. Of the ten families belonging to the first (the 
inferior), five are represented in the United States; of the 
second, which exhibits the higher organization, the whole 
ten families exist in our country. 
This system was first published at Upsal in 1860, by 
Wilhelm Lilljeborg. 
In the present book, the liberty has been taken of alter- 
ing the author’s arrangement as far as possible, and the . 
classification proposed by Lilljeborg has heen substituted. 
E. D. C. 
