22 THE MYOLOGY OF THE RAVEN. 



dilEcult to thoroughly trace in the younger specimens 

 of Ravens, and it admits of our seeing the underly- 

 ing structures throuoh it. The delicate fibres of the 

 j^latysma myoides overlie it, while^ its anterior fasciculi 

 hlend with those of the mylo-hyoideus. 



According to Mivart, in birds and reptiles the di- 

 gastric descends from the hinder part of the cranium to 

 the posterior end of the mandible, and in some birds is 

 divided into three portions (Elem. Anat., p. 313). As 

 we have just seen, it is still different in the Corvidw. 



The chief use of this muscle would seem to be to 

 raise the hyoid apparatus and trachea against the pha- 

 rynx, after a morsel of food has passed that point, to 

 prevent its return to the mouth, and assist its passage 

 down the oesophagus. 



