316 



COMPARATIVE ZOOLOGY. 



Fig. 290.— Sturgeon (Acipenser sturio). Atlantic coast. 



Fig. 291.— Oat-tioii, or .horned Pout (PimcLo&us catus). 

 American rivers. 



and a scaly exoskeleton. The skull is extremely com- 

 plicated ; the upper and lower jaws are complete, and the 



gills are comb -like 

 or tufted. The tail 

 is homocercal ; the 

 other fins are varia- 

 ble in number and 

 position. In the 

 soft -finned Fishes, 

 the ventrals are ab- 

 sent, as in the Eels ; 

 or attached to the 

 abdomen, as in the 

 S aim on s, He rri n gs, 

 Pikes, and Carps ; or 

 placed under the throat, as in the Cod, Haddock, and 

 Flounder. In the spiny-finned Fishes, the ventrals are 

 generally under or in front of the pectorals, and the scales 

 ctenoid, as in the Perches, Mullets, and Mackerels. 



4. Dipnoi. These Fishes connect the class w T ith the 

 Amphibia. They have an eel -like body, covered with 

 cycloid scales ; an embryonic notochord for a back-bone ; 



Fig. 292. — Cod (Morrhua Americana). Atlantic coast. 



Fig. 293. — Protopterm annectens; one fourth natural size. African rivers. 



