On the Cartilago palatina and the Organ of Jacobson in some Mammals. 353 



rhynchus. In Eckidna it is found in the posterior pari of the organ ; 

 however it continues forwards as a thickened, cartilaginous bar, 

 which probably is the rudiment of a turbinal once extending as far 

 forwards as the turbinal plate in Ornithorhynchus. 



In no other living mammals such a turbinal has as yet been 

 found. 



But Broom has shown that the homologue of the above-rnen- 

 tioned thickened anterior bar in Eckidna is present in the Marsu- 

 pialia iu the form of a cartilaginous bar on the outer side of the 

 organ. It has been considered as characteristic of the Marsupialia, 

 being constant in the various types of this group. 



A similar rudiment is also found in a few other lower mam- 

 mals 1 e. g. Dasypus villosus and Lepus cunicidus and among the 

 Insectivora in Macroscelides proboscideus. Its presence also in Tupaja 

 being now established, it might be considered as characteristic of 

 the Insectivora menotyphla. 



In the Insectivora lipotypbla it has not been found, until now 

 observed in Crocidura russida. 



At first sight it would seem unexpected that Crocidura should 

 have retained a more primitive type of Jasobson's organ than the 

 other shrews which have been examined, considering the less pri- 

 mitive character of this genus in other respects. As I have lately 

 shown, its dental System is on the whole less primitive than that 

 of Sorex and Neomys. In Crocidura for instance there are no 

 traces of the lower anterior incisors, which tooth-germs are very 

 distinct in the two other genera 2 . 



Another instance is afforded by the os jugale, of which I have 

 found a minute but distinct rudiment in Sorex (1. c. 1907) and, as 

 will be shown later on, also in Neomys, but of which I have found 

 no trace at all in Crocidura russula. (Having not hitherto had an 

 opportunity to examine Crocidura sacralis, in which Peters 3 pre- 

 tends to have found a rudimentary os jugale, I cannot express any 

 opinion on this discovery.) 



There are, however, in Crocidura russula some features which 

 show that this species is in certain respects no less primitive than 



i R. Broom, 1. c. 1898. 



2 A. Ärnbäck Christie-Linde, Der Bau der Soriciden und ihre Beziehungen 

 zu andern Säugetieren. II. Zur Entwicklungsgeschichte der Zähne. Ontogenie. 

 Morphol. Jahrbuch. Bd. XLIV. 1912. 



3 W. C. H. Peters, Reise nach Mossambique. I. Säugetiere. Berlin 1852. 



