On the Cartilago palatina and the Organ of Jacobson in soine Mammals. 347 



curves and continues backwards, assuming the appearence typical 

 in sections (Fig. 4). The cartilagiiies paraseptales are not attached 

 behind to other skelctal parts and extend a little farther backwards 

 than the organ itself. 



The organ of Jacobson enters the naso-palatine canal im- 

 mediately in front of the point where the nasal cavity opens into 

 this canal (Fig. 2—3). The duct-like part of the organ is very 

 short and lined with an epithelium of uniform thickness. The organ 

 itself is large and occupies almost the whole cartilaginous cavity, 

 as appears from Fig. 4. Its inner wall is lined with an epithelium 

 which resembles a sensory epithelium and is thicker than the epi- 



Fig. 3. 



Fisr. -i. 



ns. 



C'rocidura russula. Foetus (12'/'2 mm). Transverse sections of region of Jacobsons organ. c.ps. car- 

 tilago paraseptalis ; J.o. Jacobson's organ; n.p.c. naso-palatine canal; n.s. nasal septum; o.b. outer 

 bar of cartilago paraseptalis; o.s.c. outer part of sickle-shaped cartilage; pmx. premaxillary ; v. blood- 

 vessel. Fig. 3 X&O. Fig. 4 x c. 66. 



thelium of the outer wall. On the upper side of the organ, especi- 

 ally in its posterior half, there are glands openiug into the organ. 



In the other foetal specimens examined that represent nearly 

 the same stage as the one described above — the head-length of 

 which is about 8 mm ■ — I have found the cartilaginous process in 

 question, though varying as to development. 



In the oldest foetal specimen examined, in which also the 

 dental System has attained a higher degree of development than in 

 the afore-mentioned ones, the cartilago paraseptalis has a different 

 appearence, its upper part being elongated and curved; the cartila- 

 ginous outer bar is almost totally reduced, and the anterior part of 

 the organ is enclosed for a short distance by a cartilaginous ring — 



