354 A. Ärnbäck Christie-Linde 



the other above-mentioned shrews. Such a featnre is for instance 

 the presence of a rudiuientary tooth-germ between the upper fourth 

 premolar and the first molar, representing probably a supernumerary 

 molar. It is therefore in fact not very surprising to find another 

 primitive character in this animal. 



Primitive characters seem thus to be distributed among the 

 different genera of the Soricidae so that one genus can hardly be 

 said to be more primitive on the whole than the other. 



As to the phylogeny of Tupaja we as yet know very little. 

 However, the presence of the above described cartilaginous bar on 

 the outer side of Jacobson's organ indicates a low State of deve- 

 lopment. For independently of the Interpretation of the cartilaginous 

 process in question, it is a fact that, as far as is hitherto known, 

 it occurs only in lower mammals. And with regard to the sickle- 

 shaped cartilago ductus naso-palatini it is generally present in higher 

 mammals, but absent in lower ones e. g. Monotremata, Marsupialia. 



As for the cul-de-sacs of Jacobson's organ in Tupaja I find it 

 impossible at present to decide, whether they are to be regarded 

 as primitive structures or not. Nor do they allow of aoy conclusion 

 as to the function of the organ. 



Though it does not seem impiobable that the complicated struc- 

 ture of the organ in Tupaja as well as in Gymnura is due to a 

 difference of sex, my scanty material makes a decision on the point 

 impossible. I know that the young Gymnura rafflesii examined, 

 which presents the usual structure as to the epithelium of the organ, 

 is a male, but I know nothing about the sex of the other indivi- 

 dual with the folded epithelium. 



Moreover I know that the specimen of Tupaja sj)., in which the 

 cul-de-sacs are found, is a female and that the examined individuals 

 of the species T. javanica which present an epithelium of the usual 

 structure are males. 



The possibility that the structure in question is due to a dif- 

 ference of sex is thus at all events not excluded. One may hope 

 that further investigations will throw light upon the function of 

 this organ, about which we as yet know nothing at all. 



Having examined no adult Tujxija, I can State nothing as to 

 the further development of the above-mentioned cul-de-sacs. 



Considering the above, one may be justified in regarding the 

 Insectivora, especially the Soricidae, as forms intermediate between 



