THE FISHES, MOLLTTSCA, AND OTHER OBJECTS. 



Fig. 4. 



Scale of Perch. 



many, it is very at- 

 tractive. The scales 

 of the perch and 

 tench are more orna- 

 mental, the denticu- 

 lated margin of the 

 former having been 

 selected by Professor 

 Agassiz for his order 

 of Ctenoid fishes. In 

 order to view fish- 

 scales with the po- 

 lariscope, it will be 

 necessary to mount 

 them in balsam. It 

 will be seen that 

 the scale of the 

 tench differs mate- 

 rially from those of 

 many other fresh- 

 water fishes. Whilst 

 dwelling on these, 

 as objects for the 



will find in the scales of our 

 fresh-water fishes, objects 01 

 great beauty and delicacy, 

 which require only a low power 

 to develope them. Fig. 8 

 gives that of ' the pike, and, 

 although it is not so pretty as 



