Lateral Wall of the Cavum Nasi in Man. 703 



and superior termination. The superior meatus has also in 26 

 per cent of instances a cell opening into the superior recess, and in 

 50 per cent of cases a cell opening into the inferior recess. 



32. In the adult the anterior ethmoid cells open into the me- 

 atus medius. According to my series of specimens, in 100 per 

 cent of instances anterior ethmoid cells have their ostia in the 

 position of the suprabullar recess or furrow. The cells that open 

 in this position vary in number from one to three, and are directed 

 variously behind the bulla ethmoidalis. They may also be directed 

 towards the cribriform plate or towards the frontal sinus. I find 

 that in 13 per cent of cases there is an ostium of an anterior eth- 

 moid cell on the medial surface of the bulla ethmoidalis, or in the 

 position of the original bullar furrow. In 11 per ceirt of instances 

 an ostium of an anterior ethmoid cell is found in the position of 

 the infrabullar furrow. The anterior ethmoid cells that develop 

 from the frontal furrows vary in size, number, and position. These 

 cells may open directly into the middle meatus or into the supe- 

 rior and ventral end of the infundibulum ethmoidale. Some of 

 them also frequently open into the suprabullar recess. 



33. Ethmoid cells frequently extend into the body of the con- 

 cha nasalis media, the agger nasi, and the processus uncinatus. 

 These cells also at times encroach upon the cavities of the frontal 

 and sphenoidal sinuses. 



34. The ostium of the adult sinus maxillaris is frequently 

 duplicated. This may be due to a double pouching of the primi- 

 tive sinus maxillaris, or it may be developed later in a manner 

 similar to the formation of the ostium maxillare accessorium. 



35. The sinus maxillaris has, according to my series of speci- 

 mens, an accessory ostium communicating with the meatus medius 

 directly in 42.4 per cent of cases. I believe that this accessory 

 ostium is formed by the developing sinus maxillaris, i.e., the sinus 

 maxillaris developing until the medial wall of the cavity becomes 

 thinned out and attenuated in the position of the accessory open- 

 ing, until an ostium is formed. The accessory ostium is not pres- 

 ent in the fetus nor in the young child. 



36. In the adult the sinus frontalis may communicate with the 

 meatus nasi medius in one of the following ways: (1) The nasofrontal 



