656 Jacob Parsons Schaeffer. 



many cases an accessory fold or concha on the lateral wall of the 

 meatus nasi superior which is comparable to the bulla ethmoidalis. 

 These structures contained in the middle and the superior meat- 

 uses are hidden or accessory nasal conchae, comparable to the 

 accessory conchae found in mammals. In the middle meatus 

 we also note the hiatus semilunaris, and if the processus uncinatus 

 be turned inferiorly, the infundibulum ethmoidale is exposed. 

 In the superior and ventral portion of the middle meatus we note 

 varying relations in different specimens, between the nasofrontal 

 duct and the infundibulum ethmoidale and some of the anterior 

 ethmoidal cells. The ostia of ethmoid cells are also to be seen in 

 the meatus medius, superior, and suprema I — the relations of 

 these ostia varying much in different specimens. 



In order to interpret these varying adult conditions and rela- 

 tions, it is essential that we study the developmental changes in 

 the middle and the superior meatuses at some length in the 

 embryo, late fetus, and in the young child. This will at once 

 point out the probabilities of development and the varying adult 

 conditions one may expect to meet in a series of specimens. 



The accessory folds and furrows of the descending ramus of the 

 meatus nasi medius. If we examine serial frontal sections of 

 the nose of a 40-day embryo we will find that the lateral wall of 

 the meatus nasi medius is more or less even and simple. If, on 

 the other hand, we examine the same region in embryos aged 

 from 50 to 60 days we will find a somewhat crescentic shaped 

 fold with its free border directed superiorly, breaking the evenness 

 of the wall. The latter is the anlage of the processus uncinatus 

 and the first of the series of accessory folds to appear on the lat- 

 eral wall of the meatus medius. This fold at once aids in forming 

 a furrow immediately superior to it — the primitive infundibulum 

 ethmoidale. It is quite probable that the furrow first establishes 

 an anlage and this in turn throws into slight relief a portion of 

 the mucous membrane inferior to it, thus establishing the anlage 

 of the processus uncinatus. It may, however, be said that both 

 structures are more or less dependent upon each other in estab- 

 lishing anlages. The same principles are obviously here involved 



