THE CELLUL^E ETHMOID ALES 63 



as found in some adult specimens, such that the cell might 

 readily be regarded as having caused the projection into the 

 floor of a previously developed sinus. Cells of this group 

 may also extend far anteriorly sometimes even anterior 

 to the anterior wall of the ductus nasolacrimalis (Fig. 47). 



A majority (65 per cent.) of specimens from cases over two 

 years of age show a cell or a part of a cell which has developed 

 so as to produce pneumatization of the prominence termed 

 the agger nasi or nasoturbinal. The agger nasi appears in 

 the latter part of the second or the first part of the third 

 fetal month as a prominence on the anterior portion of the 

 lateral nasal wall, extending antero-inferiorly from the 

 anterior attachment of the concha media, approximately 

 parallel to the nasal bones. As a rule, the agger nasi is 

 relatively more prominent in late fetuses and infants than 

 it is in older individuals. Of the 65 per cent, of cases over 

 two years old showing pneumatization of the agger nasi, it 

 was found that in 60 per cent, of such cases the pneumatiza- 

 tion had extended from the anterior cellula frontalis (Figs. 

 36 and 51), and in 40 per cent, from the anteromedial cellula 

 infundibularis (Fig. 27). The location of these cells is such 

 as to require careful inspection by operating surgeons, lest 

 their presence be overlooked when wishing to eradicate frontal 

 and infundibular cells. 



The bulla ethmoidalis may contain either a single large 

 cell or else from two to four smaller ones. One bullar cell 

 was present in 25 per cent, of specimens, two cells in 62 per 

 cent^ three cells in 10 per cent., and four cells in 3 per cent, 

 of 202 postnatal lateral nasal walls. Of these cells, 81.7 per 

 cent, had their origin from the suprabullar furrow, and 18.3 

 per cent, from the infrabullar furrow. Whatever the num- 



