316 
COMPARATIVE ZOOLOGY. 
American rivers. 
jfiG. 290 _Sturgeon (Acipemser sturio). Atlantic coast. 
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 
Fig. 291.— (Jut-nou, ur jL.on.ea Fout ( Pimeludm catus). position. In the 
soft - finned Fishes, 
the ventrals are ab¬ 
sent, as in the Eels; 
or attached to the 
abdomen, as in the 
Salmons, Herrings, 
Fig. 292.— Cod (Morrhua Americana). Atlantic coast. T .~ 
Pikes,and Carps; or 
placed under the throat, as in the Cod, Haddock, and 
Flounder. In the spiny-finnfed Fishes, the ventrals are 
generally under or in front of the pectorals, and the scales 
ctenoid, as in the Perches, Mullets, and Mackerels. 
4. Dijpnoi. These Fishes connect the class with the 
Amphibia. They have an eel-like body, covered with 
cycloid scales; an embryonic notochord for a back-bone; 
Fig. 293. —Protopterus annectem; one fourth natural tuze. African rivers. 
