INTRODUCTION TO THE CLASS OF FISHES 163 



The body of a typical fish is wedge-shaped, narrowest at the 

 tail, thin from side to side, and the head tapers to a blunt 

 point. This form is specially designed for rapid and easy 

 progress through water. 



The Black Bass may fairly be regarded as a perfectly 

 typical fish. 



The variations from the perfect type are almost innumer- 

 able. For example: 



The Lung-Fish has foot-like fins, and practical lungs. 



The Catfish has no scales. 



Some Sharks and a few other fishes bring forth their young 

 alive. 



The Rays and Skates are the flattest of all vertebrates. 



The Climbing Perch can climb. 



The Flying-Fish can rise from the sea, and fly. 



The Lantern-Fish, of the deep sea, carries a phosphores- 

 cent light upon its head. 



The anatomy of fishes is a special branch of knowledge in 

 which the general reader can scarcely be concerned, but for 

 the ichthyologist there are many special works. Books for 

 the identification of all the known species of fishes in North 

 America are now available for those who desire them. At 

 present, however, we are concerned only with the twenty 

 great groups, or Orders, and the fifty or sixty important types 

 which represent them. Of these there must be some serious 

 study. 



Up to this date, nearly every systematic writer upon the 

 Fishes as a Class has chosen either to alter or ignore previous 

 classifications, and adopt the arrangement which to him has 



