154 FIRST LESSONS IN ZOOLOGY. 



of movement in the art of swimming. Tadpoles and frogs, 

 turtles and alligators, ducks and loons, dogs and horses, can, 

 after a fashion, get through the water ; but how clumsy and 

 grotesque are the movements of the most elegant swimmers 

 among the vertebrates with legs compared with the move- 

 ments of a fish in its natural element ! The student should 

 watch the movements of goldfish in a jar; or, better, of 

 larger fish in an aquarium. 



While in human life address, delicacy of perception, and 

 tact are important elements of success in making one's way 

 in the world, the same holds good even with bony fish. 



FIG. 159. Young Angler-fish. 



The cod's under jaw has a long barbel, or organ of touch. 

 In swimming over the bottom, or in grubbing in the mud 

 and sand, it may with this be better able to detect the star- 

 fish, snail, or crab partly hidden beneath it. Many fishes, 

 especially bottom-feeders, as the pout, etc., as well as 

 the carps, especially the barbel, are provided with barbels. 

 The angler-fish, which buries itself in the mud and sand, 

 with its mouth partly open, has along the back a row of 

 slender tactile filaments, which stand up above the surface. 

 Small fry swim along, touch the danger-signals thus hung 

 out, stupidly disregard them, and the great jaws, like a con- 



