30 ON THE LARYNX AND (ESOPHAGUS OF A COMMON MACAQUE. 



cartilage, and the entire ring is internal to the mucous lining of 

 the oesophagus. The structure round the oesophagus seems to 

 have broken into it from the cricoid cartilage. 



If the tongue and larynx are moved by the observer as they 

 do naturally when the animal swallows, the posterior part of the 

 larynx comes up against the posterior plate (text-fig. 2, B) and 

 obstructs the oesophagus. Of course, that probably does not occur 

 in life. Again, the semilunar mouth of the oesophagus is firmly 

 closed by the cartilaginous plates, and one gets the appearance 

 of a sphincter. The specimen had been preserved too long to 

 permit of a dissection of muscles which might move the posterior 

 plate, so I must leave the problem of how this animal swallowed 

 unsolved. 



Both the specimens described in this communication are now 

 preserved in the Museum of the Boyal College of Surgeons, 

 London. 



