THE NASAL REGION IN EUTAENIA. 403 



embryo head. Fig. 5 is a representation of one of these. The carti- 

 lage there seen on the lateral wall of the upper nasal cavity passes 

 down into the turbinal, bends and forms a loop, which is the origin of 

 the closed turbinal tube containing in the adult a portion of Midler's 

 Nasal Gland. It is continued downwards, and after giving off a thin 

 sheet, which is deflected between the Organ of Jacobson and the nasal 

 wall, the main portion reaches the maxillary cartilage, bends horizon- 

 tally inwards to the pedicle of the Organ of Jacobson, where it turns 

 upward and ends in a thickened rounded edge. I have not found 

 any thin plate separating the nasal wall from the Organ of Jacobson 

 in the adult. 



EXPLANATION OF PLATE I. 



.Figs. 1, 8, 9, 10 were executed by Prof. Wright. The others were drawn by 

 myself from photographic representations or by means of the 

 camera. 



GENERAL. 



'Ch. . . Choanae. 



•Chf. . . Choanal folds. 



Mdp. . . Middle palate. 



M. . . Maxillary ridges of the palate. 



P. . . Palatine ridges bounding the middle palate. 



Pc. . . Longitudinal crest of the middle palate. 



Pa. . . Palatine bone. 



Mx. . . Maxilla. 



<Gls. . . Upper lip gland. 



Mg. . . Lateral Nasal Gland of Mltller. 



J. 0. . . Organ of Jacobson. 



J. C. . Canal of the Organ of Jacobson. 



Pd. . . Pedicle projecting into the floor of the Organ of Jacobson. 



■Vo. . . Vomer. 



Tb. . . Turbinal cartilage. 



Tb'. . Cartilage of the pedicle of the Organ of Jacobson. 



.Sept. . . Nasal septum. 



.Spx. . . Septomaxillary bone. 



■Spx' . . . A portion of the vomer replacing the septomaxillary. 



Na. . . Nasal bone. 



Pra. . . Ascending process of the premaxilla. 



Lc', Ic". . . Lacrymal cartilages. 



Lop. ... Opening on the mouth of the lachrymal duct. 



Lc . . Lachrymal duct. 



Op J. . . Groove into which the canal of the Organ of Jacobson opens. 



Olf. . . Olfactory lobes. 



