388 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



In the immediate neighbourhood of the epipharyngeal bones, the 

 membrane becomes much thickened and thrown into folds, for the 

 most part longitudinal. The thickness of the membrane here is due 

 to the accumulation of striated muscidar fibres, which at the com- 

 mencement of the oesophagus forms a species of sphincter muscle. 



The passage of the pharynx into the oesophagus is of a funnel 

 form, its base being some distance posterior to the epipharyngeal 

 teeth-pads. The folds give an appearance of ribbing to the funnel, 

 this being seen most distinctly when the jaws are widely separated, 



The superior teeth-pads, one on each side of the middle line, are 

 of round or oval shape, and situated on the epipharyngeal bones. 

 The membrane surrounding and covering the pads is thin, sensitive, 

 and contractile. 



The hypopharyngeal pads are rhomboidal on surface view and are 

 placed opposite the epipharyngeals, with their long axis directed out- 

 ward and backward. 



Both sets of structures are extremely sensitive. When the 

 epipharyngeal pads are touched, the membrane shrinks, the pads are 

 thrust down, and at the same time those of the floor are elevated in 

 opposition. This is for the purpose of comminuting the food as it 

 passes into the oesophagus, mere contact of food or other matter 

 serving to bring the pads into action. 



The lining membrane of the straight oesophagus is longitudinally 

 folded, and is perfectly colorless in the fresh condition. Its muscular 

 walls are thick. Near its posterior end the oesophagus receives the 

 opening of the duct of the air-bladder. 



The folds which anteriorly are longitudinal, become arranged in 

 the stomach in every direction and disappear when it has been dis- 

 tended by, and hardened in, chromic acid and alcohol. The openings 

 of its glands are scarcely observable with the naked eye. 



The stomach of Amlurus belongs to the coecal type, the coecum, 

 however, not being distinctly marked off as such. It possesses with 

 the cardia the same axis longitudinally placed, and is short blunt- 

 cone like. Its ruyce are like those of the cardia, and both portions 

 are tinged chocolate-red when the stomach is in the digesting state. 



The pylorus, which is of smaller- diameter, starts from the left side 

 of the junction of the cardia and coecum and extends forward beside 

 the former to near its anterior termination, where a circular con- 

 striction visible on the outer surface of the pylorus denotes its 



