2Q2 ELEMENTARY ZOOLOGY. 



the bow-fin, and a few other types that are found in our 

 lakes and rivers. 



The lung-fishes (dipnoi) include three or four species 

 from widely separated parts of the world, and are remark- 

 able because of the great development of the air-bladder. 

 This becomes a real lung and is of use to them as the rivers 

 in which they live become partially dry. They are mud- 



FIG. 115. Long-eared Sun-fish (Lepornis auritus). Photo from life by Shufeldt. 



fishes. One species comes from the rivers of Australia, 

 another from South America, the others from Africa. 

 The paired appendages of these animals are less like 

 fins and more like legs or flappers. In these respects the 

 dipnoi stand somewhat intermediate between the fishes 

 and the amphibians. 



301. Economic value of fishes is very great and is des- 

 tined to become more so as we learn how to breed and care 

 for them and increase the edible forms at the expense of 

 the non-edible. It is necessary only to mention the 

 names of some of the food fishes to realize their value. 

 The salmon, the cod, the herring, the mackerel, sardines, 

 whitefish, halibut, menhaden, catfish, are some of the 

 most used fish. Hundreds of other species are edible. 



