212 MALACOPTERYGII.— CYPRINID^. 
are much coarser and less regular, often being 
interrupted, and seeming to run into each other, 
and frequently swelling into oval scars. This 
may, perhaps, be owing to the surface having 
been partially worn down by rubbing against the | 
gravel of the bottom, or against other objects in | 
the water. Besides the concentric lines, there are | 
seen on many of the scales, especially those of the 
lateral line, radiating lines varying in number 
from one to twenty or more, diverging from the 
centre towards the circumference, and frequently 
connected by cross lines forming a sort of net- 
work around the centre, (see c). Under the 
microscope these lines appear to be elevated 
ridges, dividing the concentric lines ; but of their 
use we are ignorant. | 
In the microscopical examinations which we 1 
instituted while writing these pages, we ascer- i 
tained some interesting facts. The brilliant , 
golden or silvery reflection that constitutes 
the beauty of these lovely fishes depends not on i 
the scales themselves, but on a soft layer of I 
pigment spread over their inner surface, and 
seen through their translucent substance. On | 
carefully detaching a scale, we see on the under j 
side, opposite to that portion only which was ex- |i| 
posed, all the concealed parts being colourless, a ! 
layer of soft gleaming substance, easily separable, | 
either silvery or golden, according to the hue of j 
the fish. If now we remove a small portion of J 
this substance with a fine needle, and spread it on j 
a plate of thin glass, we shall find, by the aid of j 
the microscope, that it consists of two distinct | 
substances ; the one giving the colour, the other | 
the metallic lustre. With a power of 300 | 
