CHAPTER II 

 THE EXTERIOR OF THE FISH 



|ORM of Body. With a glance at the fish as a living 

 organism and some knowledge of those structures 

 which are to be readily seen without dissection, we 

 are prepared to examine its anatomy in detail, and to note some 

 of the variations which may be seen in different parts of the 

 great group. 



In general fishes are boat-shaped, adapted for swift progress 

 through the water. They are longer than broad or deep and 

 the greatest width is in front of the middle, leaving the com- 

 pressed paddle-like tail as the chief organ of locomotion. 



But to all these statements there are numerous exceptions. 

 Some fishes depend for protection, not on swiftness, but on the 

 thorny skin or a bony coat of mail. Some of these are almost 

 globular in form, and their outline bears no resemblance to that 



FIG. 6. Pine-cone Fish, Monocentris japonicus (Houttuyn). Waka, Japan. 



of a boat. The trunkfish (Ostraciori) in a hard bony box has 

 no need of rapid progress. 



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