78 PROCEEDINGS OF THE ANATOMICAL AND ANTHROPOLOGICAL 



simply an extension of this helping to form the inner alveolar wall and 

 does not exist as a separate element. 



Meckel's cartilage becomes ossified and incorporated with that 

 part of the lower jaw below and inside the mesial and lateral incisor 

 teeth. Posterior to this point Meckel's cartilage does not enter into 

 the formation of the lower jaw. The anterior extremities of Meckel's 

 cartilages also do not enter into the formation of the lower jaw, but 



, v * 



Vi * * \ '\ 



m 



Fig. 18. Sagittal section through the coronoid 

 cartilage of the losver jaw of a human 

 foetus, 95 mm. in length ( x 33). 



Fig. 19. Coronal section through the lower 

 border of the left half of the lower jaw of 

 a human foetus, 230 mm. in length ( x 50). 

 The section is made in the region of the 

 lateral incisor tooth, and shows an acces- 

 sory cartilaginous nucleus surrounded by 

 bone. 



usually persist throughout foetal life as one or two cartilaginous 

 nodules behind the symphysis. The comparative anatomy of Meckel's 

 cartilage and the extent to which it enters into the formation of the 

 Inner jaw in various vertebrates is of interest, but I do not propose 

 t<> go into this in the present paper. It may be noted, however, that 

 in man at no stage do the anterior extremities of Meckel's cartilages 

 actually fuse in the middle line, while in the jaws of other mammals 

 which I have examined such a fusion does take place ; this is the 



