44 



STRUCTURE AND CLASSIFICA.TTON 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.— Abdominai Cavity or Bxicorvii,s. 



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

 vein ; L, liver seen through fibroiia partition mentioned" in the text. 



