350 A. Ärnbäck Christie-Linde 



of the naso-palatine canal and stretching backwards for a conside- 

 rable length. It is situated in front of the maxillary bone and between 

 the maxillary and premaxillary bones in tbe angle formed by tbe 

 medial and lateral processes of the latter. It lies quite isolated, 

 not being connected with any other skeletal parts and, in foetal 

 stages at least, forms part of the floor of the nasal cavity behind 

 the naso-palatine canal. The two cartilaginous plates do not unite. 

 They are found in the large species, Tupaja sp., as well as in the 

 specimens of Tupaja javanica examined (Fig. 6 — 8). 



As appears from the figures, there is in Tupaja no sickle-shaped 

 cartilago ductus naso-palatini, supporting the naso-palatine canal, as 

 is the case in the Soricidae and also generally in higher mammals. 

 The cartilago paraseptalis reaches as far downwards as to embrace 

 the opening of the duct-like part of the organ into this canal. 



From Fig. 6 — 7 appears, how the cartilaginous bar is connec- 

 ted with the upper end of the cartilago paraseptalis. A little farther 

 back, the bar lies detached on the outer sideof the organ of Jacob- 

 son, which is now supported on the inner and lower sides by the 

 cartilago paraseptalis (Fig. 8). Farther back still the outer bar is 

 connected with the lower end of the last-mentioned cartilage. The 

 latter now assumes the common curved or U-shaped form. It con- 

 tinues a little beyond the organ of Jacobson, thus being of some- 

 what greater length than this. It is not behind connected with 

 other skeletal parts. 



The length of Jacobson's organ is considerable, and it is rather 

 wide. It enters the naso-palatine canal immediately before the 

 opening of the nasal cavity into it (Fig. 6). 



The foremost part forms a short duct lined with an epithelium 

 of uniform thickness. 



From Fig. 9 appears that the epithelium of the inner wall of 

 the organ is many times thicker than the epithelium of the outer 

 wall and looks like a sensory epithelium. 



On the outer side of the posterior part of the organ and be- 

 hind it there are plenty of glands opening into it by many ducts, 

 especially at the upper and hindmost part. 



Along the anterior part of the organ I have observed a Single 

 blood-vessel running on its outer side; but farther back it seems 

 to be divided into several small vessels. 



In Tupaja sp., the large species from Borneo examined — which 

 is a female — , the organ of Jacobson is of a somewhat com- 



