Lateral Wall of the Cavum Nasi in Man. 



661 



In many cases there is no differentiation into superior and infe- 

 rior bullar folds by an intervening furrow — the bullar furrow. 



The inferior hullar fold or concha. The inferior bullar fold or 

 concha is, as stated above, not always differentiated from the 

 superior bullar fold. It is, however, occasionally well isolated 

 and stands more or less as an independent fold (figs. 34 and 39). 



ttifi/tj^fs 0/ 

 II. elli. out.) 



Cel/ulii cth- 

 mouialis pm 

 tenor (ouloi^t) 



hi/, et/i 



i>. ma.i 



Figs. 32 and 33 Photomicrographs of frontal sections through the right nasal 

 fossa of a 7-months fetus (series B slide 31). Section fig. 32 is through 'the 

 ventral portion, and section fig. 33 is through the dorsal portion of the fossa. 



The frontal furrows have pouched towards the frontal region in the establish- 

 ment of early anterior ethmoid cells (fig. 32). 



See page 662 for explanation of lettering. 



The latter condition is especially marked in the cases where an 

 anterior ethmoid cell develops from the bullar furrow (fig. 39). 

 I agree with Killian that the superior and inferior bullar folds 

 (obere und mittlere Nebenmuscheln, Killian) usually coalesce 

 to form the adult bulla ethmoidalis. Sometimes, even in the 

 adult, we see evidences of the primitive bullar furrow, which more 

 or less grooves the medial surface of the adult bulla. In many 

 instances coalescence is, however, not necessary because there 

 was at no time a differentiation into two portions. 



