THE CELLULE ETHMOIDALES 53 



small ridges developing from the posteromedial surface of 

 the processus front alls of the maxilla. These small ridges 

 are the conchse frontales, and from the furrows or depres- 

 sions between them, or between them and the surround- 

 ing walls of the recess, the cellulse frontales develop. In 

 Killian's studies of a large number of specimens from late 

 fetuses and infants three conchse frontales were found to 

 represent the complete number; thus four cellulse frontales 

 may develop. This type of development is shown in Fig. 36. 

 However, the development is usually not so complete (Figs. 

 20, 21, 38, 43, 51, and 53). Two conchse frontales are 

 usually found in postnatal specimens, though in some cases 

 only one, and in still others none, is demonstrable. 



All the furrows between the frontal conchse (whatever 

 number may be present) do not necessarily develop into 

 cells. Specimens from older children, as well as from adults, 

 show that some form distinct cells, some persist as simple 

 concavities in the anterolateral wall of the recess, and others 

 have disappeared or else were never present. These cells 

 are important factors in the development of the sinus 

 frontalis, 59.4 per cent, of the sinus frontales in this series 

 having had their origin from one of the cells lying medial to 

 the processus uncinatus. 



The manner in which the processus uncinatus is attached 

 to the agger nasi, its relations to the bulla ethmoidalis, and 

 the character of the attachment of the anterior portion of 

 the concha media, exert the greatest influence upon the pro- 

 portion between the number and size of the cellulse frontales 

 and the cellulse infundibulares. If the processus uncinatus 

 is attached to the posterolateral portion of the agger nasi 

 and the anterosuperior attachment of the concha media is 



