PLATE 3 



EXPLANATION OF FIGURES 



5 Mid-coronal section of syrinx, X 8^. Adult male. 



6 Mid-coronal section of syrinx, X 85. Adult female. 



7 Transparent drawing of wax reconstruction of epithelial tube and con- 

 densed mesenchyma in region of tracheal bifurcation. Ventral aspect, X 50. 

 176 hour chick embryo. 



206 



