GENERAL OUTLINES OF ICHTHYOLOGY. 25 



in whicli each series of scales are placed cross each other 

 nearly vertically, showing a figure resembling the letter X, 

 or a sort of double cone, the scale in the centre forming 

 the apex of each cone. Each scale is attached to the skin 

 by its anterior, or more forward, edge, which fits into a sort 

 of pocket, or ' follicle ' ; but the manner in which the scales 

 overlap each other is variable. 



The scales on different parts of the body are of different 

 sizes; and those down the side, forming the lateral line, 

 are pierced through in the centre with openings, to allow 

 the escape of a fluid which lubricates the skin beneath. 

 Examples of these are annexed. 



Scale from lateral line of Basse. Scale from lateral line of Ruft'e. 



The heads of most fish also possess these openings (or 

 muciferous orifices, as they are termed) usually in greater 

 numbers than the other parts of the body ; and this dis- 

 tribution is one of the most beautiful arrangements of 

 Nature. The mucus or slime by which the scales of fish 

 are as it were varnished, or waterproofed, being exuded 

 from the pores of the head, is necessarily carried backwards 

 by the current — or, in still water, by the progressive motion 

 of the fish — and spreads itself over the whole surface of the 

 body. The lubricating fluid is most abundant in fish with 



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