344 Jacob Parsons Schaeffer. 
largest sinus found in the whole series. Although the cavity in 
the male averages slightly larger than that of the female, a 
reference to table C will show that sex affects the size of the sinus 
but shghtly. 
The following may be given as average measurements of the 
adult sinus maxillaris, based on the measurements of 90 speci- 
mens: 
num. 
! _Dorsosuperior diagonal. sa, oe 2. ae Reb Po en Nh 38 
2 Vienbrosupenlor dra conmals, meena se cots eae ae ee eats ene 38.5 
Bd SUperolmher On Mets senses eee eae TIS cen rae tg setae eae ene peenn 33 
Aim (Viembrod Onsale eis cei cssra ese ie eee Ce teed meee ease cae ete 34 
Br IMediolaberall.. cus d vx heey acca pat Ses mie ene ye ita Nene ae neue a 23 
Due to the great differences in the several measurements, the 
capacity of the sinus, in different individuals, must also differ. 
The range in capacity, of the sinuses studied to ascertain this 
fact, was from 9.5 ce. to 20 ec., with an average of 14.75 ce. 
The tables A, B and C show the range of measurements. 
The conditions which produce these varied differences in the 
dimensions of the sinus maxillaris may be readily ascertained. 
Take for example the following two conditions which showa marked 
difference in the mediolateral plane and yet the other measure- 
ments are inversed: 
No. ; VoD; M. L. Soule IDS TS; 1D) Vien) 
mm. mm. mm. mm. mm. 
Le Aer AE 30 18 40 41 41 
2 30 30 35 40 30 
In case number 1 the- lateral nasal wall was markedly bulging 
towards the sinus. In consequence of this encroachment, the 
mediolateral distance was greatly lessened. In case 2 the recessus 
alveolaris was poorly developed, hence the short ventrosuperior 
diagonal in comparison with the respective measurement in case 
number 1. These cases show that even though a sinus may greatly 
exceed another in one of its measurements, it may be exceeded in 
size in its other planes. 
Again there may be a great difference in the ventrodorsal dis- 
tance. This means a marked inpushing of the ventral wall of the 
