262 PROCEEDINGS OF THE ACADEMY OF [1888. 



nearly vertical, in 47 both sides inclined moderately outward, 3 had 

 right side vertical and left inclined, 4 had the left side vertical and 

 right inclined, and in 9 the inclination was undetermined. 



Second, the extraordinary modifications in the proportions of the 

 face. The face stunted as it is in its anteroposterior dimensions 

 compensates for this defect in a great tendency to downward growth. 

 The premaxilla is enormously thickened as it enters into the com- 

 position of the mouth ; the sides of the vault including the alyeolar 

 processes are greatly elongated ; and the sutural line of the maxillse 

 tends to become hyperostosed in the region of the rugse or a separate 

 exostosis forms back of it on the free surface of the palate. It has 

 been seen how the presence of the hyperostosis modifies the shapes 

 of the ruga\ The firm suture between the premaxilla and the 

 maxilla determines the greater size of the ruga which answers to it. 

 The sides of the vault drag the lateral part of the rugie of the post- 

 sutural set from a horizontal to a vertical and forward position. 

 The median hyperostosis breaks the rugse into parts, — a condition 

 never seen so far as I know in any quadruped. The changes are in 

 illustration of the well known law that peripheral structures are 

 conformable to the deeper lying tissues with which they are in 

 correlation. 



One of the most conspicuous appearances in the human rugie is 

 the approach of two or three folds towards one another either at the 

 median or lateral ends. It is most marked in children in the lat- 

 eral ends (where they are clustered toward the deciduous canines 

 and molars) and in the adults at the median ends anteriorly. 



The third and fourth rugse of the right side have marked special 

 dispositions to incline forward and inward, often cutting off the first 

 and second folds or causing them to disappear. The convergence may 

 go so far as to effect union between the different folds. Especially 

 is this the case between the sutural fold and the third on the right 

 side, by means of which the forked appearance is seen (see fig. 8). 

 In some examples the sutural fold is united with the third be- 

 hind, and with the pre-sutural in front. 



In 90 specimens examined I found the lateral ends of the left rugae 

 convergent in 19; the lateral ends of those of the right side in 10; 

 and on both sides in 11. 



In the same number of specimens I found the median ends con- 

 vergent in the lefl side in 6, on the right side in 4, and on both 

 sides in 5. 



