HAIRS, FEATHERS, AND SCALES. 



19 



line. Along each side, in most fishes, may be observed a 

 line, known as the lateral line, formed by scales of pecu- 

 liar form. They are commonly more bony than the 

 other scales, and are pierced by a tubular orifioe for the 

 escape (as is generally supposed, though this has been 

 denied) of a mucous secretion, which is poured out from 

 glands beneath, and thus Hows over the body for the 

 double purpose of protecting the skin from the mace- 

 rating influence of the surrounding water, and of 

 diminishing friction in swimming. 



Let us now look at some scales of the cycloid kind. 

 The great majority of our fishes are clothed with such 

 as are of this description. This dead Gold-fish shall give 

 us examples. The three scales in the upper row are from 



SCALES OF GOLD-FISH. 



the lateral line, the left-hand one (a) taken just behind 

 the head, the second (b) near the middle of the body, and 

 the right-hand one (c) near the tail. Of the lower row, the 

 first (d) is from the back, the second (?) from the middle 



c 2 



