LUNQ-FISH. 



the common garpike. In others, 

 however, as in the Amia and Dip- 

 noans, the scales are rounded or 

 cycloid. The sturgeons (Fig. 193) 

 have the snout long and pointed, 

 with the mouth underneath, and 

 toothless, while the body is pro- 

 tected by very large scales. Aci- 

 penser sturio is the common sea- 

 sturgeon of our coast, ascending 

 rivers. The shovel-nosed sturgeon,. 

 ScapMrhyncliops platyrliynchziff, 

 has a spade-like snout. It inhab- 

 its the waters of the Mississippi 

 Valley. 



The singular spoon-bill, Polyo- 

 doii folium (Fig. 194), is five feet 

 long, smooth-skinned, has a snout 

 one third as long as the body, and 

 spatulate, with thin edges. It has 

 a very wide mouth, with minute 

 teeth, and lives on small Crus- 

 tacea. It abounds in the Missis- 

 sippi and its larger tributaries. 



The Dipnoi or lung-fishes are 

 so-called from the fact that often 

 being in pools and streams liable 

 to dry up, they breathe air directly, 

 having true lungs, like those of 

 frogs, as well as gills. From the 

 nature of their brain and 3-cham- 

 bered heart, the Dipnoans are quite 

 different from all other fishes, while 

 on the other hand the notocord 

 is persistent. 



The body of the Dipnoans is 

 somewhat eel-shaped, though not 

 very long in proportion to its thick- 



S--) 



