136 



J. PARSONS SCHAEFFER 



minates blindly (indicated by a probe) as a cellula ethmoidalis 

 anterior (infundibular cell) lateral to the recessus frontalis. 

 Loose interpretation of the anatomy of this region in this in- 

 stance, might lead to the erroneous statement that the sinus 

 frontalis developed as an extension of the infundibulum eth- 

 moidale. One sees even a channel-like depression on the lateral 

 wall of the recessus frontalis connecting in a sense the sinus 



Si/i/)> froi/tcdis. . . 

 Troieue ductus /^ffsotrof/tah. 

 CelluJa efh. a/^t. , 

 



Coii(I'C( uas . wcfL 

 J//f>mdrb. d/y- - ■ - 



free. u?//:7/iat'/.->- -r" 



X.--'" ' 



CeJluIae efh . a/it 



CfUuh/ (fh. (mt.(md) 



Cclluhfc dJf./fost. 



0sf?/j7N spkt/wdi/Je 



\ Co ncha //as. supre/ual 



Co?/cJia 7(a^.siip- 



° _ " V\ . Co// r//. a /I a s. inf. 



Fig. 8 From an adult. Dissection shows tlie nasofrontal connections and the 

 ethmoidal labyrinth exposed. Especially note the derivatives of the frontal pits 

 and the direct continuity of the sinus frontalis with the infundibulum ethmoidale. 

 The dorsal blind end of the infundibulum ethmoidale, due to a mucosal fold (A') 

 passing from the free border of the processus uncinatus to the bulla ethmoidalis, 

 should also be noted. In this specimen practically all secretion from the sinus 

 frontalis would find its way into the sinus maxillaris. See text. 



frontales with the infundibulum ethmoidale. It is obvious that 

 drainage from the sinus frontales would in part find its way into 

 the infundibuhnn ethmoidale, thence via the latter to the ostium 

 maxillare and into the sinus maxillaris (antrum of Highmore). 



In figure 7 we have evidence of four embryologic frontal pits. 

 The derivatives of these pits are two cellulae ethmoidales anterior 

 and two sinus frontales, all in communication with the recessus 



