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Iii all birds, except nocturnal ones, the head is 

 smaller, and bears less proportion to the body than ii\ 

 beasts, that it may the more readily divide the air in 

 flying. Their eyes also are more flat and depressed, 

 and a circle of small plates of bone, placed scale-wise 

 under the outer coat of the organ, encompasses the 

 pupil on each side to strengthen and defend it from in- 

 juries. Besides this, birds have a kind of skin called 

 the nictitating membrane, with which, like a veil, they 

 can at pleasure cover their eyes, though their eyelids 

 continue open. This membrane serves also to wipe, 

 cleanse, and probably to moisten its surface. The 

 eyes, though they outwardly appear but small, yet 

 each almost equals the brain ; whereas in man the 

 brain is more than twenty times larger than the eye. 



Hence it follows that the senso of seeing in birds U 

 infinitely superior to that of other animals. Indeed 

 this piercing sight seems necessary to the creature's 

 support and safety. Were it not so, from thfi rapidity 

 of tlie bird's motion, it would be apt to strike against 

 every object in its way, and it could scarcely fwdsub. 

 sistence unless it could discern its food from above with 

 astonishing sagacity. A hawk, for instance, perceives 

 a lark at a distance, which neither men nor dogs could 

 spy ; and a kite, from an almost imperceptible height 

 darts down on its prey with the most unerring aim. 



Granivorous birds, or such as live upon vegetables, 

 have their intestines differently formed from those of 

 the rapacious kind. Their gullet dilates just above the 

 breast. bone, and forms itself into a pouch or bag called 

 the crop. This is replete with saliva! glands, which 

 moisten and soften the food it contains. After the dry 

 food of the bird has been macerated, it passes into the 

 belly, where, instead of a soft moist stomach, as in 

 the rapacious kinds, it is ground between two pair of 

 muscles, commonly called the gizzard, covered on the 

 inside with a strong ridgy coat. These coats rubbing 

 again jt each o*her, are capable of attenuating thf 

 hardest substances ; their action being often compar. 

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