30 Effie A. Eead 



(Fig. 23). These are plate-like bones and are roughened and per- 

 forated (Fig. 11), but not plicated, as in dog and cat (Figs. 17, 20). 



The superior turbinated bone is attached to the cribriform plate and 

 is more or less united to the median one which lies ventrad to it (Figs. 

 11, 23). The inferior is just dorsad of the palate (Figs. 11, 23). The 

 extent of the turbinated bones is relatively much less in man. 



The nasal cavity is divided into three regions according to the nature 

 of the epithelial lining. 



The vestibule or cephalic part of the nose is lined with stratified 

 epithelium which is continuous with the epidermis. In the respiratory 

 region (regio respiratoria) the epithelium is replaced by the columnar 

 ciliated type (Fig. 43), 



The olfactory region (regio olfactoria), with which this paper deals, 

 is adjacent to the cribriform plate. In fresh material the mucosa is 

 slightly yellow, due to the pigment in the sustentacular cells. The 

 extent of this area is relatively much greater in dog and cat than in 

 man. In dog and cat it comprises about I/2 of the numerous ethmo- 

 turbinals (Figs. 1, 3, 5), and from ^/g to I/2 of the nasal septum (Figs. 

 2, 4, 7, 8). With reference to the three sinuses opening into the nasal 

 cavity, viz., the sphenoidal, the maxillary and the frontal, only 

 branches of the 5th nerve could be traced to the mucosa of the sphenoidal 

 and maxillary. This is in agreement with previous workers. In works 

 on human anatomy (Quain, Piersol) only the 5th is given as inner- 

 vating the mucosa of the frontal sinus. 



In the dog and cat there is one scroll (Jayne) of the ethmo-turbinal 

 extending for a short distance into the funnel-like opening of the 

 frontal sinus. This may be in the form of a somewhat curved leaf, the 

 free margin dividing the funnel-like outlet in part or the scroll may 

 be rolled up more completely so that the free end in the frontal sinus 

 is curved and looks like the open mouth of a snail shell. Olfactory 

 nerves ramify in this scroll. In the dog they extend also for some 

 distance into the mesal mucosa covering the bony wall of the sinus 

 opposite the cribriform plate. In the cat the scroll-like projection is 

 more lateral and the mucosa lining the sinus opposite the orbit has the 

 greater number of olfactory nerves. That is, in the dog the olfactory 

 nerves of the mouth of the frontal sinus are toward the middle line, 

 while those in the cat are lateral in position. The brown coloration of 

 the epithelium in the olfactory part of the sinus is marked. From the 

 position of the olfactory nerves in the cephalic part of the sinus and its 



