

A. Sturgeon (Chondrostei) 



B. Gar pike (Holostei) 



Closed duct~\ 



C. Typical Teleost 



Esophagus 



Vascidar- 

 J bi-lobed 

 ^ bladder 



I 



D. Crossopterygian 



E. Dipnoan 



Fig. 124. Comparative Anatomy of the Swim Bladder. Observe the evolu- 

 tion toward a closed hydrostatic bladder in the Teleostei, and toward a 

 ventral lung in the Dipnoi. (Adapted from Dean). 



