704 Jacob Parsons Schaeffer. 



duct or the sinus frontalis may open directly into the meatus 

 medius; (2) The nasofrontal duct may be directly continuous 

 with the infundibulum ethmoidale ; (3) The nasofrontal duct may 

 be continued down to the infundibulum ethmoidale and meet the 

 latter structure at varying angles ; (4) The sinus may have two 

 nasofrontal ducts which in turn may have either of the above 

 relations with the cavity of the nose ; (5) Rarely the sinus fron- 

 talis communicates directly with the sinus maxillaris. 



37. In some case the sinus frontalis has no true nasofrontal 

 duct, but the sinus cavity itself extends well down into the supe- 

 rior and ventral portion of the meatus medius. 



38. It is not common for the infundibulum ethmoidale to be 

 directly continuous with the nasofrontal duct. As a rule the naso- 

 frontal duct meets the infundibulum ethmoidale at varying angles. 

 There is frequently a shallow groove connecting the two channels. 

 However some specimens show that the infundibulum is directly 

 continuous with the nasofrontal duct. 



39. If we include the cases in which the infundibulum eth- 

 moidale is directly continuous with the nasofrontal duct, and those 

 in which the nasofrontal duct meets the superior and ventral end 

 of the infundibulum ethmoidale at an angle, they will represent 

 approximately 56 per cent of my specimens. The specimens in 

 which the nasofrontal duct communicates directly with the meatus 

 nasi medius will include approximately 46 per cent of my specimens. 

 The cases in which no nasofrontal duct is present, and those in 

 which two nasofrontal ducts present are distributed among the 

 above specimens, since they can all be thus classified. 



40. From a practical point of view the infundibulum ethmoidale 

 acts as a gutter communicating between the frontal region and 

 the maxillary sinus in 56 per cent of my cases. 



