1 68 



BACKBONED ANIMALS. 



FIG. 207. Young of the 

 Nile Polypterus, show- 

 ing external gills, br. 



a. ray and spine (Fig. 207). The 

 young have external gills (Fig. 

 207, br). 



Order IV. Garpikes (Hyoga- 

 noidei). The garpikes (Fig. 208) 

 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 (Lepidosteus osseus). 



Sub-Class III. BONY FISHES (Teleostei). 



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).-^^ eels are without ventral fins. 

 The Anguilla 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 



