On the Cartilago palatina and the Organ of Jacobson in sonie Mammals. 363 



10 mm — no cartilago palatina was to be seen. In such an early 

 stage it is not yet developed. In comparison with other cartilages 

 its development seems to be retarded. 



With this the following Statement of Geosser 1 harmonizes: 

 »Bei Embryonen von Vesperugo pipistrellus zeigt sich, daß dieser 

 horizontale Anteil des hinteren lateralen Knorpels in dem schon 

 vorhin erwähnten Stadium (8 l / 2 mm Scheitel-Steißlänge), in welchem 

 der septale und paraseptale Knorpel bereits als Vorknorpel, die 

 übrigen Knorpel als Bindegewebsverdichtung erscheinen, überhaupt 

 noch nicht angelegt ist.« 



But, at least in the young embryo of Tupaja javanica, the naso- 

 palatine canal is already formed. It has consequently been formed 

 independently of the cartilago palatina. It is probable that, though 

 in lower mammals this cartilage may have been necessary for the 

 formation of the naso-palatine canal, the latter may, during the 

 course of development, have grown more and more independent of it. 



However, it is not absolutely improbable that in some mammals, 

 f. i. Tupaja and Chirogaleus, where the cartilago palatina is com- 

 paratively well developed, it might partially serve as a floor of the 

 nasal cavity in foetal stages, completing the not yet fully ossified 

 secondary palate. It always keeps the same position, supporting 

 the naso-palatine canal laterally and behind. 



According to Grosser in Chiroptera the cartilago in question 

 has a special function. Grosser writes: »Die Cartilago posterior 

 hat bei den Glattnasen eine eigene Bedeutung gewonnen; sie bildet 

 eigentlich den Boden der Nasenhöhle im Bereiche des Ausschnittes 

 des harten Gaumens. Zu diesem Behufe nimmt der Knorpel in 

 geringer Entfernung caudal vom Ductus incisivus eine horizontale 

 Lage ein und verbreitert sich beträchtlich. — « 



It may however be pointed out that the cartilago palatina is, 

 as mentioned above, by no means less developed in Pte?vpus, in 

 which bat there is no »Ausschnitt des harten Gaumens«. The high 

 development of this cartilage in Chiroptera may therefore be due 

 to some other cause. Nor is it probable that the horizontal posi- 

 tion of the cartilage is due to any special function in Chiroptera, 

 as it has the same position in other animals in which it has attained 

 some note-worthy degree of development. 



1 0. Grosser, 1. c. p. 17. 



