14 THE COMMERCIAL SEA FISHES OF 



common receptacle of water passing to the gills for respira- 

 tion, and food transmitted to the stomach for nutrition ; 

 while, as might be anticipated, its capacity is large and 

 variously formed. But the several purposes to which the 

 mouth is employed, and the means by which such are 

 effected, it is not my purpose to enter upon, except to 

 remark on the absence of the salivary glands, which in 

 some forms appear to be represented by some mucous 

 follicles that open into the mouth below the side of the 

 tongue, much saliva doubtless being unnecessary, owing to 

 the moist condition of the food. Teeth are of various 

 forms and differently disposed in the different families and 

 genera, in fact, more especially in the osseous forms, there 

 is a tendency for the mucous membrane in almost any part 

 of the mouth, throat, or gills, to develop teeth. The gastric 

 portion of the intestinal canal consists of an oesophagus 

 and a stomach, between which a cardiac constriction is not 

 so frequently observable as a more or less abrupt change 

 in the structure of the lining mucous membrane. In some 

 forms at the lower end of the stomach and the com- 

 mencement of the small intestines, a constriction occurs 

 termed the pylorus. It must be observed that the 

 orifices of the two ends of the stomach are usually in 

 bony fishes more or less approximating, in order that 

 the food may be retained as in a caecum. Occasionally 

 the stomach is situated not in the direct course, but to one 

 side, as it were, of the intestinal canal. Another constric- 

 tion, marked internally by a more or less well-defined 

 internal valve, shows where the small intestines terminate 

 and the large ones begin. 



Should the intestinal canal be slit up, and its inner 

 surface examined, the commencement of the stomach is 

 generally observed to be defined by increased vascularity, 





