640 Jacob Parsons Schaeffer. 



cases the differentiation in the ethmoidal region is not carried so 

 far as in some others, hence a smaller number of ethmoidal con- 

 chae. 



Whatever the number of ethmoidal conchae may be, there is a 

 corresponding number of meatuses or furrows; i.e., each concha 

 more or less overhangs a furrow or meatus. This overhanging is 

 especially marked in the meatus nasi medius. Killian gives six 



Leieiiil pliilr of 

 rartilntje 



~ ', Srjtfum nasi 



• 1-, >^ Chonita 



Fig. 20 (X 10) Outline drawing of a frontal section through the dorsal portion 

 of the nasal cavity. The section (slide 91) is from the same embryo as are those 

 represented in figs. 17, 18, 19. Note how the dorsal and superior portions of the 

 nasal fossae establish the anlages of the sinus sphenoidales. 



as his highest number of ' Hauptfurchen'- — this would place a 

 meatus dorsal and superior to the most cephalic concha present. 

 I, however, prefer to think of this region as belonging to the reces- 

 sus sphenoethmoidalis. The latter because it corresponds to 

 the position of the adult recessus sphenoethmoidalis; also that 

 after birth we do not usually think of the meatus nasi as being 

 superior to, but inferior to the corresponding conchae nasales. 

 The recessus sphenoethmoidalis, however, is very closely related 

 to the meatus nasi suprema I, and in the absence of the latter 

 with the meatus nasi superior. 



