168 BACKBONED ANIMALS. 
br a ray and spine (Fig. 207). ae 
ESV VF oung have external gills (Fig. 
CwWes a an 
Sie) aon Wannye eh tha Order IV. Garpikes (Ayoga- 
Nile Polypterus, show-  motdet).—The garpikes (Fig. 208) 
ing external gills, 67. have beak-like jaws with sharp 
teeth; the scales are large and re- 
semble white enameled plates. The air-bladder is lung- 
like, and the fishes are often seen at the surface inhaling 
air. They occur in the Western and Southern rivers and 
Great Lakes. The eggs are hatched the last of May. 
The scales are used as arrow-tips by some Indians. 
FIG. 208.—Garpike (Lepzdosteus osseus). 
Sub-Class III. Bony Fisues ( Ze/eoséet). 
General Characteristics—In these fishes (Figs. 193, 
194) bone takes the place of cartilage. The skull is com- 
posed of many bones; the optic nerves cross each other ; 
the gills generally number four pairs, and have several 
opercular or protective bones, 
Eels (Apodes).—The eels are without ventral fins. 
The Axguilla is common in the United States, living in 
fresh-water streams, but depositing its eggs, often 8,000,- 
ooo to a single fish, in the ocean, the young ascending the 
rivers. The sexes are difficult to distinguish ; the females 
have the highest dorsal fin, smaller eyes, and a lighter color 
than the males, while the snout is generally broader at the 
tip than in the male. The conger-eel attains a large size, 
and ranges from Newfoundland to the West Indies. In 
