Lateral Wall of the Cavum Nasi in Man. 



635 



and the most ventral of the anterior group of ethmoidal cells. 

 The accessory folds and furrows, and the frontal recess of the 

 middle meatus will be considered in detail in a subsequent por- 

 tion of this paper. 



Septum uai 



Concha natafit 

 media 

 Meatus nasi 

 medius 



Meatus naxt 

 commutth 



ProcensuM uneinatvs 



\ Tnfundibiilum 



^^<^=^ eihmoidale 



Meatus nasi 



inferior 

 Concha nasaiis 



inferior 



Fig. 17 (X 10) Outline drawing of a frontal section through the nose of an 

 embryo aged 120 days (Human embryo, No. 42, Cornell University series, slide 

 29). 



At this plane of section the processus uncinatus is fused with a frontal fold, 

 and the infundibulum ethmoidale ends blindly. Compare this figure with fig. 18. 

 In the latter figure the plane of section is farther dorsal. 



The early changes in the meatus nasi superior 



With the appearance of the accessory folds (conchae) and the 

 frontal recess of the middle meatus^ we have the estabhshment, 

 in very many cases, of the anlage of an accessory fold (concha) 

 on the lateral wall of the superior meatus. This fold early tends 



