FIG, 13 
STURGEON 
AND MANY 
TELEOSTS 
LEPIDOSTEUS 
ann = «6AMIA 
ERYTHRINUS 
CERATODUS 
POL YPTERUS 
AND 
CALAMOICHTHYS 
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 unpaired character of the organ, its varied mode of attachment 
to the digestive tube, and the smooth or convoluted condition of its lining mem- 
brane. 
22 
