CHAPTER XXII. 



CHORDATA (CONTINUED): CLASS FISHES. 



293. General Statement. Most of the fishes that the 

 student will find are so characteristic that he will have 

 no trouble in recognizing them at once. They are in- 

 teresting because of their graceful and rapid motions in 

 the water, for which the shape of their body so well 

 adapts them, and for their strength and gameness when 

 caught. They constitute the largest class of vertebrates 

 and are found in all waters, fresh and salt. They vary 

 in length from one-half inch up to the great basking- 

 shark which may be as much as thirty-five or forty feet 

 in length. 



The body is commonly elongated, pointed at both ends, 

 and thin from side to side; but we find all sorts of de- 

 partures from this, in certain cases, in adjustment to 

 special kinds of life. Some fish become nearly globular; 

 others are long and snake-like, as the eels. The ribbon 

 fishes are long and flat; the skates are flat from back to 

 belly. Many deep-sea fishes are quite grotesque in form. 



Many fishes, particularly in tropical waters, are highly 

 colored; and in many instances the coloration is such as 

 to give protection to the possessor, though this is by no 

 means always true. 



294. External Features: Appendages and Scales. 

 The appendages of fishes have the form of fins. These 

 are folds of the skin supported by rays of harder material. 



281 



