Lateral Wall of the Cavum Nasi in Man. 647 



uncinatus as the descending crus of the agger nasi, and speaks of 

 the two structures as his ''erste Hauptmuschel." In commenting 

 on Killian's classification of the nasoturbinal (agger nasi), Peter, 

 who studied the structure from a comparative point of view, says : 

 ''Killian und vor ihm Andere glaubten auch dass das Nasotur- 

 binale in das Schema der Riechmuscheln einzwangen zu miissen 

 und suchten daher nach einem Crus descendens desselben, den 

 sie im Processus uncinatus gefunden zu haben meinten. Nach 

 obiger Darstellung der Muschelentwicklung ist diese Forderung 

 ebenso umberechtigt, wie sie ftir das Maxilloturbinale ware." 



I prefer to think of the processus uncinatus as an accessory 

 concha, and to class it with the folds of the bulla ethmoidalis 

 (also accessory conchae of the middle meatus) and with the acces- 

 sory concha of the superior meatus. While the processus uncina- 

 tus is more or less continuous with the agger nasi, and for descrip- 

 tive purposes might be considered as the descending crus of the 

 agger nasi, it is also in many instances fused ventrally and superi- 

 orly with the lateral surface of the concha nasalis media. I have 

 also seen it fused across the infundibulum ethmoidale with the 

 ventral extremity of the bulla ethmoidalis. In subsequent para- 

 graphs I will consider the concha nasalis media as Killian's 

 "zweite Hauptmuschel," and will not consider the agger nasi and 

 the processus uncinatus as belonging to the regular group of 

 ethmoidal conchae. 



The concha nasalis media, superior, suprema I, suprema II, 

 suprema III. The regular group of ethmoidal conchae have many 

 things in common, hence may for the time be considered together. 

 In a general way they all possess knees or bends, thus presenting 

 superior and inferior, or better, ascending and descending por- 

 tions (Crura ascendens and descendens of Killian). As we pass 

 from the concha media to the concha suprema III, we find a grad- 

 ual lessening in the degree of the knee or bend. The supreme con- 

 chae represent practically straight angles, hence no well marked 

 division into ascending and descending crura, i.e., the conchae 

 are practically straight. This is also aided in very many cases by 

 the rudimentary development or complete absence of individual 

 ascending crura (figs. 23 and 29). As we pass from the concha 



