Clark : An Accessory Naso-Frontal Duct.1 



[Phil. Journ. Sci., Vol. V, No. 5. 



Os. froatale 



Slaus frontalis, (j.^ frontal cell) 



1st. frontal cell. 



Dilatation in ductus 

 naso-f rontalis. 

 Ostium ductus 



na.50- frontalis 



Ductus na50-lacrima.lis. 



fltrium meatus nasi mcdii. 



ContXa >\n.soAis Mv^exic 

 S-nus n\a)!i\\.o.<is 



Ductus 



no-^b-fronfalis. 

 access 



fltrium 

 na-si 



L rt«ra.t * 



Ist.frontal cell 



Sinus frontalis (i-'-f rental cell.) 



4th frontal cell- 



ctlrmoi.cla.lis r\- 



i°esa hasalis 



Lafnmfl. cnbros 

 a.h.d. seprum. 

 nasi reflected 



Fossa cranii nrvecUa,. 



Neruus opticus 

 'Corpus ossis SfjKenoi.ia.lis 

 15'cn.us spKcnoiAalis. 



Fig. 2. 



PLATE 



