FISHES 



123 



extremely difficult. Who would think, for instance, that such ani- 

 mals as the sea horse (Fig. 91) and the pipefish (Fig. 92) would be 



FIG. 92. Pipefish. 



classed with the perch and goldfish? Yet such is the case, since 

 careful study has shown that these forms have all the charac 

 teristics mentioned in 89. 



dorsal fin 



anal fin 

 FIG. 93. Flounder. 



pelvic fin 



It is evident that the goldfish and perch have bodies that are 

 considerably longer than they are wide or deep, and this is true of 

 most of the common fishes. In the group of fishes known as the eels, 



