LUNG-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 sturgeoU; 
Scapliirliyncliops p la tyrliynch us^ 
has a spade-like snout. It inhab- 
its the waters of the Mississippi 
Valley. 
The singular spoon-bill, Folyo- 
don 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- 
