FISHES. 



commonly overlapping. " By maceration in 

 water, scales exhibit a series of laminae, the 

 smallest in size having been the first produced ; 

 they resemble a cone, the apex of which is out 

 wards, the smallest bein 



^ in the centre ; hence 



^_ 



SCALES OF FISHES. 



the appearance of numerous concentric lines, all 

 of the same shape, which mark the growth."* 



Along each side, in most fishes, may be ob- 

 served a line, known as the lateral line, formed 

 by scales of peculiar form. They are commonly 

 more bony than the other scales, and are pierced 

 by a tubular orifice for the escape of a mucous 

 secretion, which is poured out from glands be- 

 neath, and thus flows over the body for the 

 double purpose of protecting the skin from the 

 macerating influence of the surrounding water, 

 and of diminishing friction in swimming. 



The organs of motion in this Class are the 

 fins. They generally take the form of a delicate 



* Yarrell, British Fishes, Introd. xii. 



