84 



STRUCTURE OF FISFIES. 



larly those that are found on the pharyngeal bones, and which 

 serve to grind the food when on its way to the oesophagus. 

 They have no true salivary glands ; the oesophagus is very short. 



Fig. 45.* p 



ANATOMY OF A PIKE. 



24. The other viscera of the digestive apparatus, (Fig. 45.) 

 are lodged in the abdomen, which is lined by a peritoneum, and 

 separated from the cavity containing the heart by a sort of 

 diaphragm, (s.) In some fishes, (chiefly the cartilaginous fishes,) 

 the abdomen communicates externally by two openings, situate 

 upon the sides of the anus, so that the peritoneum is continuous 

 with the skin. 



25. The stomach, (i.) is in general, very distinct ; that part 

 which corresponds_ to the large intestine, is not much larger than 

 the small intestine; and there never is a ccecum as in mammals. 

 The liver, (m.) is generally large, and of a soft texture ; the 

 position and size of the gall-bladder, (.) vary ; the place of the 

 pancreas is almost always supplied by two tubes of a peculiar 

 tissue, placed around the pylorus ; the position of the anus varies 

 much ; sometimes it is found under the throat, and at others, at 

 the base of the tail. The kidneys, (p.) are very voluminous, and 

 extend along both sides of the vertebral column, the whole length 

 of the abdomen. Their excretory ducts terminate in a sort of 

 bladder, the opening of which is posterior to the anus. 



* Explanation of Fig. 45. Anatomy of the viscera of a Pike : a. the 

 nostrils, b. the cavity of the mouth, c. a part of the lower jaw, d. the 

 tongue, e. the branchiae, or gills,/, the arch of the palate, or roof of the 

 mouth, p. openings through which the water passes from the mouth to 

 the branchiae. h. the oesophagus, t. the stomach, j. the intestine, k. 

 the anus, m. the liver, n. the gall-bladder, o. the duct of the gall-bladder, 

 p. the kidneys, q. the urinary Madder, r. the heart, s. the diaphragm, 

 t. the brain, u. the spinal marrow, v. the swimming-bladder or air- 

 vessel. 



24. Where are the chief organs of digestion situate? 



25. What are the general characters of the digestive organs? 



