CHAPTER VIII 



FISHES 



NO branch of the animal kingdom offers a more 

 bewildering range of forms or a greater medley 

 of contrast in its ways of life than does the group 

 of animals collectively spoken of as "fish." Fish are 

 especially adapted for a life in the water, the majority 

 being elongated and " streamline " in form. The surfaces 

 of their bodies, which are usually covered with scales, 

 are thus free from irregularities that might impede pro- 

 gression when swimming. 



In most fish the fins, which vary greatly in size and 

 number, are what is termed "paired" and "unpaired," 

 the former corresponding to the limbs of the higher 

 terrestrial animals. The paired fins are represented by 

 the pectoral or breast fins and the pelvic or abdominal 

 fins, the unpaired by the dorsal or back fins, the caudal 

 or tail fin, and the anal fin, which is situated on the under 

 surface of the fish close to the base of the tail. 



The pectoral fins, which are usually used for the purposes 

 of steering, may likewise be employed to assist it in various 

 other functions, such as in climbing — as in the case of 

 the Mud Skippers, or even flying — as in the case of the 

 Flying Fish and Gurnards. 



The Mud Skipper (Periophthalmus) is a fish living in 



120 



