Lateral Wall of the Cavum Nasi in Man. 701 



15. The first change on the lateral nasal wall from a more 

 or less even surface is the production of very shallow grooves. 

 The latter appearing inferior and superior to the position of the 

 primitive concha nasalis inferior (maxillary fold). These shallow 

 grooves at once throw into slight relief the greater portion of the 

 lateral nasal wall — the anlage of the concha nasalis inferior. 



16. Shortly after the first a second fold appears, outlining the 

 anlage of the ethmoidal conchae. 



17. From three to five ethmoidal conchae become differen- 

 tiated before birth. 



18. The ethmoidal conchae in a general way present ascending 

 and descending crura. The ascending crura are, however, in many 

 cases not well differentiated. At times the ascending crura are 

 represented by a general ascending-crural mass, but individual 

 ascending crura are not outlined. 



19. The ethmoidal meatuses, including the meatus nasi medius, 

 also in a general way present ascending and descending rami. 

 The descending rami are, however, by far the most marked. In 

 fact many ethmoidal meatuses have no ascending rami. The as- 

 cending ramus of the meatus medius is the best outlined. Occa- 

 sionally the meatus superior possesses a well marked ascending 

 ramus. 



20. The integrity of the ethmoidal conchae and meatuses 

 depends upon the descending limbs rather than upon the ascending 

 limbs. 



21. The ascending and the descending rami of the meatus 

 medius present accessory conchae and furrows which are compar- 

 able to structures found in other mammals. 



22. The descending ramus of the meatus superior also pre- 

 sents &ti accessory concha on its lateral wall. It is at times well 

 marked, and again it may be very rudimentary or be entirely 

 wanting. 



23. In the region of the knees or bends of the ethmoidal con- 

 chae we frequently find lobules, and on these lobules secondary 

 nodules are occasionally seen. 



24. The descending ramus of the concha nasalis media very 

 frequently presents furrows on its medial surface. One of these 



