356 



A. Ärnbäck Christie-Linde 



läge in tliis animal. Its foremost part has the form of a vertical 



narrow plate situated on the outer side of the naso-palatine canal, 



and its posterior part widens into a horizontal plate of considerable 



length, which passes below the organ of Jacobson, forming part 



of the floor of the nasal cavity between the premaxillary and the 



maxillary bones (Fig. 13 — 14). It is better developed in the Pro- 



simiae tban in Tupaja as appears from a comparison between the 



figures. 



Fig. 12. 



n.s. 

 pmx. ' 



c.p. 



Sorex araneus. Foetus (13 mm). Transverse section of region of Jacobsons organ. c.p. cavtilago 

 palatina; c.ps. cartilago paraseptalis ; J.o. Jacobson' s organ; n.s. nasal septum ; pmx. premaxillary. xlOO. 



A sickle-shaped cartilago ductus naso-palatini is present, con- 

 nected with the cartilago paraseptalis. But in the stages examined 

 of these three specimens of Chirogaleus I could observe no con- 

 nection — at least no cartilaginous one — between the cartilago 

 palatina and the cartilago ductus naso-palatini. 



Though it seems most probable that in Galago the cartilage 

 in question is isolated as in Chirogaleus, I shall give no decided 

 opinion on this, the series of sections at my disposal not being 

 quite unbroken: a section is wanting on the very critical point. 



As far as I could see, the Prosirniae examined do not, in re- 

 gard to the organ of Jacobson and the ca'rtilages referred to it, 

 differ in other respects from the other monodelphs in general. 



The homologization of the cartilago palatina orTers some diffi- 

 culty. The first question which arises here is, whether the carti- 

 lages designated in the same way in Soricidae, Tupaja and Pro- 



