218 GYRATORES. COLUMBAD^. 



FAMILY I. COLUMBAD^E. 



(Pigeons.) 



The Pigeons have the beak of moderate length, 

 somewhat slender, swollen towards the tip, which 

 is curved downwards : the base of the upper man- 

 dible is covered with a soft skin, inflated on each 

 side, in which the nostrils are pierced. The wings 

 vary in length, and in adaptation to powerful 

 flight. The feet are comparatively short ; the toes, 

 divided to the base, are arranged three in front, 

 and one behind ; they have no spurs. 



HEAD OF PIGEON. 



" One part of the internal organization of the 

 Pigeon is worthy of special notice. The crop, in 

 the state which is adapted for ordinary digestion, 

 is thin and membranous, and the internal surface 

 is smooth ; but by the time the young are about 

 to be hatched, the whole, except that part which 

 lies on the trachea [or wind-pipe] becomes thicker, 

 and puts on a glandular appearance, having its 



