The Age and Growth of some Eels from a Worcestershire Pond. 13 
The skin is then moistened again with water, and the scales 
are easily removed by scraping it with a sharp dissecting knife 
and placed in water. 
If the skin has been properly cleaned in the way just stated, 
one* can count the zones at once, otherwise one must macerate the 
scales for about twenty-four hours, or even more, and centrifuge 
them, changing the water several times. 
The most useful powers for scale work are 1^ in., 1 in., and 
J in., and a microscope with a Porro prism is most convenient to 
work with, as any interesting or curious scale can be selected with 
the greatest ease. 
Instead of slides I prefer to use spoiled stereoscopic plates, and 
recommend, according to the size of the stage of the microscope, 
either 6 by 13 cm., or Yerascope size. 
It is well to examine some twenty to thirty scales taken from 
