212 MALACOPTERYGII. — CYPRINIDiE. 



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 

 instituted while writing these pages, we ascer- 

 tained some interesting facts. The brilliant 

 golden or silvery reflection that constitutes 

 the beauty of these lovely fishes depends not on 

 the scales themselves, but on a soft layer of 

 pigment spread over their inner surface, and 

 seen through their translucent substance. On 

 carefully detaching a scale, we see on the under 

 side, opposite to that portion only which was ex- 

 posed, all the concealed parts being colourless, a 

 layer of soft gleaming substance, easily separable, 

 either silvery or golden, according to the hue of 

 the fish. If now we remove a small portion of 

 this substance with a fine needle, and spread it on 

 a plate of thin glass, we shall find, by the aid of 

 the microscope, that it consists of two distinct 

 substances ; the one giving the colour, the other 

 the metallic lustre. With a power of 300 



