Lateral Wall of the Cavum Nasi in Man. 685 



of this accessory concha, which at times is well formed. Since 

 the fetus gave evidence of developing cells from the two recesses 

 mentioned we would in the adult expect to find ostia of posterior 

 ethmoidal cells in these positions. Twenty-six per cent of my 

 specimens showed a posterior cell opening in the position of the 

 superior recess, and in 50 per cent of cases a posterior cell opened 

 in the position of the inferior recess. 



To recapitulate: The posterior ethmoidal cells open into the 

 meatus nasi superior and suprema I. The latter meatus is present 

 in 62.5 per cent of adult cases, and in 75 per cent of instances this 

 meatus has a posterior ethmoidal cell communicating with it. 

 The superior meatus has in 100 per cent of cases a cell communicat- 

 ing with it at its ventral 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. 



These adult conditions justify our conclusions with reference 

 to cell-anlages in the fetus and young child. 



The anterior group of cells. It will be recalled that we referred 

 to anlages of anterior ethmoidal cells in both the ascending and 

 descending rami of the meatus nasi medius, i.e., in the regions of 

 the bullar furrows and the frontal recess. If now we examine a 

 series of adult specimens we will notice in the positions of the 

 former cell-anlages that we now" have ostia of cells. My series 

 of specimens indicate that in 100 per cent of cases anterior eth- 

 moid 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. They are directed variously behind the bulla eth- 

 moidalis, thus causing the latter structure to be hollowed out 

 and shell-like and at times excessively large. Some of the cells 

 with their ostia in the position of the suprabullar recess may also 

 be directed towards the cribriform plate or towards the frontal 

 sinus. I find in 13 per cent of instances that there is an ostium 

 on the medial surface of the bulla ethmoidalis, or in the position 

 of the original bullar furrow (fig. 31). In 11 per cent of cases an 

 ostium is found in the position of the infrabullar furrow. The 



