192 J. PARSONS SCHAEFFER 



passageway is proven by the fact that the lumen of the duct lead- 

 ing from the meatus nasi medius was lined with similar epithelium 

 to that lining the remainder of the ductus nasolacrimalis. 



If in the cases, where we have an extensive coalescence between 

 the strand of epidermal cells and the nasal mucous membrane 

 (fig. 14), the whole area of coalescence should become patent, 

 we would readily duplicate some of the other adult types of ostia 

 represented in the plate, figs. 1 to 11, making due allowance for 

 changes in the further development of the ostium. 



I wish to take this opportunity for expressing grateful acknowl- 

 edgment to Professor Kerr for sending me a series of specimens 

 for study from the Cornell anatomical collection. The other 

 material studied was from the Yale anatomical series. Fully 

 two hundred ostia nasolacrimalia were included in this investi- 

 gation. 



