NO. 2 LUNGS OF THE ALLIGATOR REESE II 



Fig. 7. — A wax reconstruction of the respiratory tract of the embryo shown 

 in figure I. 



Fig. 8. — A reconstruction, on paper, of the respiratory tract of an embryo of 

 slightly later development than the one shown in figure 1. 



Fig. 9. — An outline of an embryo somewhat older than the one represented in 

 figure 8. 



Fig. 10. — A camera sketch of a wax reconstruction of the entodermal re- 

 spiratory tract of the stage shown in figure 9. The extreme right of the 

 figure is in the region of the pharynx, where the trachea begins to separate 

 from the oesophagus. 



Figs. 11 to 18. — Transverse sections through the respiratory tract in the planes 

 shown on figure 10. 



Fig. 19. — A reconstruction, on paper, of the entodermal lung of the right side 

 (together with the trachea and oesophagus) of a later stage than the one 

 represented in figures 10 to 18. 



Figs. 20 to 23. — Transverse sections through the embryo represented in figure 

 19, in the planes of lines 20 to 23 of that figure. 



Fig. 24. — A reconstruction, on paper, of the mesodermal lung on the right 

 side of an embryo of about 7 cm. length. 



Figs. 25, 26. — Transverse sections through the embryo represented in figure 

 24, in the planes of lines 25 and 26. 



Fig. 27. — A ventral view of a dissected embryo of about 15 cm. length, show- 

 ing the respiratory and other organs. 



Fig. 28. — An outline of the respiratory organs of an alligator of about 75 cm. 

 length. 



