FIG, 13 
ap. STURGEON 
AND MANY 
TELEOSTS 
LEPIDOSTEUS 
AND AMIA 
ERYTHRINUS 
CERATODUS 
POLYPTERUS 
AND 
LEPIDOSIREN 
AND 
PROTOPTERUS 
Figs. 13-19. — Air-bladder of fishes, shown from the front and sides. Cf. p. 
264. A, Air-or swim-bladder. AD. Air duct. D. Digestive tube. (After WILDER.) 
13. Sturgeon and many Teleosts. 14. Amia and Lepidosteus. 15. Erythrinus, a 
Cyprinoid Teleost. 16. Ceratodus. 17. Polypterus and Calamoichthys, 18, Lepi- 
dosiren and Protopterus. 19. Reptiles, birds, and mammals. The diagrams illus- 
trate the paired or impaired character of the organ, its varied mode of attachment 
to the digestive tube, and the smooth or convoluted condition of its lining mem- 
265 
