ALIMENTARY CANAL AND ITS APPENDAGES 309 



. -J26. DIAGRAM OF THE ORAL CAVITY AND PHARYNX IN A FISH (A), 

 AN AMPHIBIAN (13), A REPTILE (C), AND MAN (D). 



Ch, internal nostril ; D, alimentary canal ; A', gill-slits ; L, lung ; N, external 

 nostril ; 0, oesophagus ; T, trachea ; the arrow marked A indicates the 

 respiratory passage, that marked B the nutritive passage ; f, the point where 

 the two passages cross one another. 



