NATURAL SCIENCES OF PHILADELPHIA. 



257 



1888.] 



intervals of equal size or are clustered at the alveolar border op- 

 posite the bicuspids. 



P'iGUKE 2. 



The arch is flat and wide, the ruga; entire; no hyperostosis is 

 present ; moderate lateral concresence is seen on the left side. 



When the two parts, (the median and the lateral) are contiguous 

 the rugoe may be said to be entire. But when they are separated 

 by intervals more or less appreciable they may be said to be broken. 

 In palates of a moderate curvature i. e. midway between the flat and 

 the high vaults, the folds may be evenly disposed and be without break 

 on one side while they are irregular and broken on the other. The 

 left side is commonly the most developed, a feature which the rugae 

 exhibit in common with the mandible, the left ramus of which is 

 commonly the larger. 



An elliptical exostosis which i(s often met with on the roof of the 

 mouth is almost always larger on the left side. The left sutural 

 ruga (see fig. 3) is generally prolonged back farther than is the 

 right. A similar disposition is seen in the first post-sutural ruga 

 but to a less degree. The post-sutural rugae especially on the right 

 side (see fig. 9) may extend obliquely forward. The third is com- 

 monly so placed, but the fourth, fifth and even the second may il- 

 lustrate this disposition (see fig. 8). As opposed to exostosis the 

 term hyperostosis will be employed to denote the general excess of 

 bone deposition along the line of the intermaxillary suture. It is a 



