A CLINICAL STUDY OF THE SKULL. 63 



suture and projects from the lower anterior margin of the nasal cham- 

 ber. These changes on the line of union of the maxilla with the malar 

 bone, and with its fellow of the op])osite side of the body, indicate that 

 the direction of pressure during the growth of the bone has been 

 greater at the sides toward the malar bone and at the median line of 

 the face than elsewhere. It has been least between themaxillse and 

 the nasal bones and between the maxillae and the palatals, which 

 would indicate that the maxilla has grown forward and from side 

 to side earlier and more aggressively than it has grown upward and 

 backward. In this statement it is assumed that each nasal bone lies 

 above the ascending process of the maxilla rather than in front of it. 

 The backward extension of the maxilla against the palatal bone in 

 the line of the dental ai'ch demands special consideration, since it 

 belongs to the means of accommodation of the molar teeth. Such 

 as it is, however, the pressure of the extending bone in this direc- 

 tion leads to increased thickening of the palatal bone in all directions, 

 and forms the pyramidal process. This process may be looked upon 

 as an exemplification of an active suture-formation, which leads 

 to hyperostosis of a part, although only one of the bones interested 

 becomes entirely involved. 



The maxilla in two places shows the effects of nerves and vessels 

 in modifying suture lines. The roof of the infra-orbital canal 

 is closed in a variable manner by the approximation of two portions 

 of the maxilla at the inferior border of the orbit. Very commonly 

 the border is thickened and an additional element of roughness and 

 unevenness presented to that already noticed in the malo-maxillary 

 suture. In like manner the maxilla as it joins the malar bone at the 

 orbito-temporal septum exhibits one to three fissures in the imma- 

 ture bone (for the accommodation of minute vessels and nerves), 

 which by the closure determine the positions of new grooves. Now, 

 the growtli in the direction of the orbito-temporal septum is vari- 

 able. The maxillary process may reach the sjjhenoid bone or it 

 may terminate at the malar. If it attains the bone first named, 

 the malar bone is excluded from the spheno-maxillary fissure. If it 



