44 



STRUCTURE AND CLASSIFICATION OF BIRDS 



is occasionally presented by birds in which the horizontal 

 septum is very short, and therefore almost vertical in direc- 

 tion. But in the birds mentioned the septa are perfectly 



FIG. 29. ABDOMINAL CAVITY OF Biicurriis. 



rj, gizzard ; a, baud of muscular fibre connecting it with oblique septum ; b, umbilical 

 veiu ; //, liver seen through fibrous partition mentioned in the text. 



