636 



FISHES. 



2. The width and strength of the maxillary of the adtdt 



fish. To show this character in two distinct species, we have 



given woodcuts of the maxillaries of females (12 inches long) 

 of S. fario and S. levenensis of the same size. 



A B 



Fig. 288.— Maxillary of A. Salmo fario ; B. Salmo levenensis. 



In young specimens of all Salmonoids the maxillary is com- 

 paratively shorter and broader, somewhat resembling that of 

 Coregonus ; yet this bone offers a valu- 

 able character for the determination of 

 the young of some species; for in- 

 stance, in a young S. cambricics it ex- 

 tends scarcely to below the centre of 

 the eye, whilst in S. fario of the same 

 size it reaches to, or even beyond, this 

 point. 



3. The size of the teeth, those of the 

 intermaxillaries excepted. 



4. The arrangement, and tJie per- 

 manence or deeiduousness of the vomer- 

 ine teeth. — In some species the vomer 

 is normally armed with a double or 

 single series throughout life, although. 



Fig. 289.— Vomerine teeth of course, some of the teeth are fre- 

 of Salmo saiar (Salmon). A. q^jgntly accidentally lost; in others, 



fame view. B. Lower view. j- ^ 



these teeth disappear gradually with 

 age, the hinder ones first, so that finally the anterior only 

 remain. In order to ascertain the arrangement of the teeth, 

 it is necessary to remove the gengiva. Frequently the teeth 

 stand in a distinctly double or single series, or they are placed 

 alternately; but frequent irregularities occur which render 



