1888.] NATURAL SCIENCES OF PHILADELPHIA. 271 



and teeth taken in plaster with great care.' The material therefore 

 is not of the average. It is based upon the hard palate of individ- 

 uals known to have some disease associated with disturbed states of 

 secretion of the nasal chambers. 



In order that the study should have a more extended application 

 it was thought to be desirable before any exact clinical conclusion 

 could be drawn that a study of similar extent be based on material 

 known to be derived from entirely healthy individuals. 



To make such examinations I visited the State Eastern Peniten- 

 tiary in this city and by the courtesy of Dr. W. D. Robinson, the 

 physician of the Institution, was enabled to fctuby the mouths and 

 nasal chambers of the inmates. In this way ninety examinations 

 were recorded. 



In no instance was hyperostosis present in the form spoken of in 

 the foregoing pages. Nor was a single case of hyperostosis of the roof 

 of the mouth back of the region of the rugae seen. In a word no form 

 of rugae was detected which was broken by the descent of the median 

 structures. 



In twenty-two examples the raphe was sufficiently prominent to 

 form a slight fullness which could be felt by the finger. The re- 

 maining fifty-eight examples were perfectly smooth. 



The inigae were very commonly of the form exhibited in Figs. 1 

 or 2 with a disposition for the folds to be concrescent at their outer 

 ends. The examples of the left sutural rugae deflected along the 

 line of the raphe, were but six in number ; moderate degree of 

 asymmetry of the sides of the roof in seven ; concresence of the 

 right sutural and post-sutural as to form a fork-like figure in but 

 three. 



It is evident that the variations of the arrangement of the rugae 

 were within a much narrower range than in the ninety cases from 

 subjects from other sources. 



The roof of the mouth presented no narrowing of the vault with 

 compression as seen in Fig. 8, and no flat wide palate as seen in 

 Fig. 9. Thus the extremes of variation — viz., of the high narrrow 

 vault and the low, wide vault were absent. But one instance of a 

 moderately compressed vault was seen and in this example the 

 pre-maxillae w^ere not thrown forward. 



1 I desire in this connection to acknowledge my indebtedness to many of my 

 friends especially to Dr. L. Ashley Faught, Dr. E. C. Kirk and Dr. J. M. McGrath. 

 Dr. J. W. White and Dr. W. Storer How of the S. S. White Dental iMfg. Co,, also 

 greatly aided me in the investigation. 



