72 THE PHILOSOPHY 



■entirely of feathers. They have no pendulous fcrotum, no bladder, 

 no flefliy uterus. Neither have they an epiglottis, though many of 

 them poflefs great powers of modulation, and fome of them may 

 even be taught to articulate words. To lighten their beaks, they 

 are deprived of lips and teeth j and their abdomen or belly is pro- 

 portionally fmall and narrow. 



From this general- view of the external figure and ftrudture of 

 birds, it is apparent, that Nature has defigned them for two diftindt 

 kinds of motion. They can, at pleafure, either walk on the furface 

 of the earth, or mount aloft, and penetrate the airy regions with 

 prodigious fwiftnefs. 



Some peculiarities in the internal ftrudture of birds deferve our 

 notice. 



Like quadrupeds, the feathered tribes are divided into granivo- 

 rous and carnivorous; and their manners and difpofitions correfpond 

 with their internal and external conformation. 



In the granivorous clafs, the oefophagus or gullet runs down the 

 neck, and terminates in a pretty large membranous fac, called the 

 ingluvies, or craw, where the food is macerated, and partly dilTolved 

 by a liquor fecreted from glands fpread over the furface of this fac. 

 Some birds, as the rooks and the pigeon kind, have the power of 

 bringing up the food from this fac into their mouths, and feeding 

 their young with it in a half digefted form. After macerating for 

 fome time, the food pafles through the remainder of the gullet into 

 another fpecies of llomach denominated ventriculus fuccenturiatus^ 

 which is a continuation of the gullet. Here the food receives a far- 

 ther dilution. From this fecond ftomach, the food is tranfmitted to 

 the gizzard, or true ftomach, which confifts of two very ftrong 

 3 mufcles, 



