</ 



344 A. Ärnbäck Christie-Linde 



mammals l . It has not been observed before in the Insectivora, ex- 

 cept in Macroscelides proboscideus 2 , though several genera of tkis 

 group have already been examined. 



In Tupaja, and also in some other mammals, I have observed 

 a small cartilage situated on the outer side of the naso-palatine 

 canal and behind it, which, being most probably homologous with 

 the processus palatinus in Eehidna, I have called the cartilago 

 palatina. 



Soricidae. 



Sorex araneus. 



A renewed examination of the organ of Jacobson in the foetal 

 Sorex araneus, of which I have now examined several more foetal 

 stages, has convinced me that nothing essential is to be added to 

 the description that I have already given, except that the outer 

 part of the sickle-shaped cartilage — to which I have given the 

 name of cartilago ductus naso-palatini — continues backwards for 

 several sections as a thin cartilaginous plate, forming a highly 

 rudimentary floor of the nasal cavity between the premaxillary and 

 maxillary bones. Its hindmost part is horizontal and broader than 

 the ' part lying immediately behind the uaso-palatine canal, which 

 part looks like a string. It is this plate that I have regarded as 

 a rudimentary cartilago palatina. It passes backwards close under 

 the cartilago paraseptalis, as appears from the Fig. 12 representing 

 a section, somewhat obliquely laid, through these parts. The plates 

 do not unite in the middle, nor are they connected with other skele- 

 tal parts. They disappear immediately before the maxillary bones. 



The cartilago palatina is also to be traced, though with re- 

 gard to the horizontal part much reduced, in the new-born Sorex. 

 In the adult animal the outer part of the sickle-shaped cartilage 

 disappears immediately behind the naso-palatine canal, and no car- 

 tilago palatina can be seen. 



There is in foetal specimens a marked difference between the 

 epithelium of the inner and that of the outer wall in the posterior 



1 E. Bhoom, A contribution to the comparative anatomy of the mam- 

 malian organ of Jacobson. Trans. Roy. Society of Edinburgh. Vol. XXXIX. 

 Part I. 1898. 



2 R. Broom, On the organ of Jacobson in the Elephant-Shrew [Macrosce- 

 lides proboscideus). Proceed. Zool. Society London. Vol. I. 1902. 



