very rapid fliers, though they are all birds of con- 

 siderable power of flight. They are, however, all, 

 at the same time, birds which are tolerably active on 

 their feet; and the large notches in the sternum, 



posteriorly towards the sides, enable them to make 

 use of their feet, by the flexure of this part of the 

 sternum, while the average production of the sternal 

 crest or keel admits of tolerably powerful muscles for 

 putting the wings in motion. They are so numerous 

 and so diversified in their habits, that no one type 

 can be properly expressive of them all, but their gene- 

 ral character is that of uniting habits on the wing and 

 on the ground in nearly equal proportions ; and upon 

 comparing their sternal apparatus with those of the 

 birds of powerful wing and the ground birds, it will 



