THE SMELT -rZo 



of sharks on our Northeastern coast, of which the dog-fishes 

 and the sand-shark are the commonest (Fig. 283). They are 

 all carnivorous animals and powerful swimmers. They feed 

 on the larger crustaceans and fish. 



The living Ganoidei are a remnant of a very extensive group 

 which existed in geological times. North ^-Vmerica is especially 



Fig. 306. — Lepidosteus, the garpike. One-eighth nat. size. After Tenncy. 



rich in existing representatives of this group, as of several 

 other old groups, such as the turtles, tailed amphibians, and 

 the king-crab. Oi the fi^'e families of ganoids, four are repre- 

 sented in this country. In the following four paragraphs a 

 type of each of the native famihes is considered. 



The sturgeons have five rows of bony scales on the trunk 

 and four barl^els on the head.' They occur both in the sea 



Fig. 307. — Amia crdva, the bowfin. One-sixth nat. size. From Leunis. 



and in the Great Lakes and the rivers of the Central States. 

 Although of large size, they feed for the most part on small 

 aquatic aninials, such as worms, insect larvae, and small fish. 

 The flesh of some species is much used as food ; the eggs taken 

 from the ovaries (roe) are pressed into a delicacy known as 

 " caviar." 



iPig. 305. 



