FISHES IN GENERAL. 125 



LESSON XXIII. 



PISHES IN GENERAL GILLS FORM AND COLOURS 



HABITS AND CHARACTER EYES EARS 



MIGRATIONS. 



THE next class of living beings embraces the 

 fishes. These dwell only in the water, and 

 differ from the three preceding classes in their 

 mode of breathing. Fish have no lungs, but 

 in their stead have on each side of the neck a 

 very curious and delicately fringed organ called 

 the gills. By means of these, fish breathe, that 

 is, a constant stream of water is passed over them, 

 the air contained in which operates much in 

 the same way as when taken into our lungs. 



The form of fish is in general very pleasing, 

 and their colours are in many instances strikingly 

 beautiful, the skin being either glossy, or covered 

 L2 



