OMNIVOROUS BILLS. 173 



Stomach. But these do not pass the pylorus into 

 the intestinal canal. They remain in the stomach 

 till all the parts fit for the nourishment of the birds 

 are separated, and then they are discharged by the 

 mouth in sapless balls, called "castings," or quids. 

 The species which have this habit cannot, of course, 

 feed upon animals of any considerable size — not 

 larger than they can svt^allow, because they cannot 

 masticate ; and though an owl can separate the 

 viscera of its prey, it is not capable of disjointing the 

 bones even of a mouse. 



We have entered somewhat more into details 

 respecting the bills of this order of birds than we 

 shall be able to do with those of the remaining orders ; 

 but they are not only well marked in their structure 

 and habits, they are also in no small degree the typical 

 members from which a general notion of the class 

 can be best formed. 



OMNIVOROUS BILLS. 



In the order of Cuvier's classification, an outline 

 of which has been given in a former section, the 

 bills of the dentirostres should follow those of the 

 birds of prey; but though these have generally 

 a notch in the upper mandible, and often in the under 

 one, none of them has the bill suited for tearing the 

 recent flesh of warm-blooded animals, as in the fal- 

 cons, and their claws are so formed as to be organs of 

 motion and support, and not killing instruments. 

 Their general habit, if birds which are so diversified 

 in their appearances, powers, haunts, and manners, 

 can be said to have a general habit, is that of feeding 

 upon insects and their larvae, in what may be called 

 the " free state ;" that is, when they are so situated as 

 that birds have not to hawk for them on the wing, or 



