360 Jacob Parsons Schaeffer. 
the infundibulum does not receive as much fluid in a given 
time. 
Class (e) fortunately represents a rare condition. Here the 
sinus frontalis draii.s Cirectly into the sinus maxillaris. In the 
specimen I found with this direct relation there was also a com- 
munication between the infundibulum ethmoidale and the sinus 
frontalis. Cryer, Bryan, and Brophy have reported direct rela- 
tions between the two sinuses, which I have been able to verify 
in this one specimen. In cases where the lateral wall of the in- 
fundibulum ethmoidale is largely wanting, fluid from the frontal 
sinus (providing the infundibulum ethmoidale is continuous with 
the nasofrontal duct) will pass almost directly into the sinus 
maxillaris, and will, therefore, very closely simulate a direct 
communication between the two sinuses. A probe passed from 
the sinus frontalis will, in such cases, also pass into the sinus 
maxillaris. Doubtless some of these cases have been considered 
by some clinicians as direct communications, whereas a further 
dissection would have proved them otherwise (fig. 26). 
The question now arises—what happens to the fluid that has 
reached the superior and ventral end of the infundibulum eth- 
moidale? In the first place it may be said that the efficiency of the 
infundibulum ethmoidale, as a carrier of fluid, is in direct ratio 
to its depth and to the degree of overhanging of the mucous 
membrane from the free border of the processus uncinatus of the 
ethmoid bone. In some cases the processus uncinatus is so nar- 
row that the infundibulum ethmoidale has no appreciable depth 
at its superior end, and in these cases the fluid which has reached 
it from the frontal region will soon leave the shallow groove 
after entering it—at least a goodly portion of it. In other cases 
the processus uncinatus is broad, and the resultant infundibulum 
ethmoidale deep and channel-like. It must also be recalled that 
in a previous paragraph mention was made of the fact that fre- 
quently the infundibulum ethmoidale ends dorsally in a pocket, so 
situated that it will direct the flow of fluid coming to the dorsal 
end of the infundibulum ethmoidale into the ostium maxillare— 
thence into the sinus maxillaris (the ostium maxillare being 
patent) (figs. 28, 29). 
