150 STRUCTURAL AND SYSTEMATIC ZOOLOGY 



FIG. 124. Garpike (Lepidosteus osseus). Lake Ontario. 



FIG. 125. Sturgeon (Acipenser sturio). Atlantic coast. 



FIG. 126. Catfish, or Horned Pout (Ameiurus nebulosus). American rivers. 



FIG. 127. Cod (Gadus callarias}. Atlantic coast. 



SUBCLASS III. Dipnoi 



These fishes connect the class with the Amphibia. 

 They have an eel-like body sometimes four or five feet 

 long, covered with cycloid scales ; an embryonic noto- 

 chord for a backbone; long, ribbonlike pectoral and 

 ventral fins, set far apart ; two incompletely separated 

 auricles, and one ventricle ; and, besides gills, a cellular 

 air bladder, which is used as a lung. 



They live in muddy or stagnant water in which there 

 is little oxygen for respiration, not enough to be obtained 



