338 Jacob Parsons Schaeffer. 
to the concha nasalis inferior, the instrument could readily be 
pushed through the soft structures of the cheek, unless the point 
were directed well superodorsally. 
RIDGES, CRESCENTIC PROJECTIONS, AND SEPTA ON THE SINUS 
‘ WALLS. 
It is important to note how frequently the walls of the sinus 
are found uneven. ‘These irregularities may consist of mere 
ridges or of different sized crescentic projections. The crescentic 
projections have been reported occasionally replaced by septa 
which completely divide the sinus into two cavities, each hav- 
ing its independent opening into the nasal fossa, but not com- 
municating with each other (fig. 22). The smaller ridges are of 
little consequence and may be omitted from further consideration. 
The larger ridges and crescentie projections, on the other hand, 
tend to form pockets and recesses, of varying depths, within the 
cavity. The septa, when they exist, may be placed either supero- 
inferiorly or ventrodorsally; thus forming either ventral and dor- 
sal, or inferior and superior compartments, respectively. Accord- 
ing to Zucherkandl’s findings, the superior and dorsal cavities 
communicate with the meatus nasi superior, and the ventral and 
inferior cavities with the infundibulum ethmoidale. Bruhl found 
the inferior compartment communicating with the meatus nasi 
inferior. Gruber found a complete division of the sinus maxil-- 
laris in 2.5 per cent of cases. 
In the material used for this paper no sinus was found show- 
ing division into two distinctly separate compartments, but the 
specimens repeatedly showed crescentic projections and ridges 
which formed pockets of a greater or less depth (figs. 18 to 23). 
Sixty sinuses were examined to cover this phrase of the work, 
with results as follows: 
NUMBER RIDGES OR CRESCENTIC SINUS WALLS 
EXAMINED PROJECTIONS EBYEN 
60 29 31 
It must be borne in mind that, in the 29 positive sinuses, 
quite a number of them showed mere ridges—the latter will be 
omitted from further study. The remaining number of the 
