CHAPTER It 
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 
Fic. 6.—Pine-cone Fish, Monocentris japonicus (Houttuyn). Waka, Japan. 
of a boat. The trunkfish (Ostracion) in a hard bony box has 
no need of rapid progress. 
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