G12 THE ORGAN OF JACOBSOX IX MARSUPIALS, 



where the palatine process is first seen distinct from the pre- 

 maxilla, the inner part of the nasal-floor cartilage curves markedly 

 upwards and sends out a well marked though feeble plate into 

 the inferior septal ridge. At the lower angle of the nasal-floor 

 cartilage there is sent down a short pi'ocess into the gap between 

 the premaxilla and its palatine process. 



Immediately following this plane we have the remarkable con- 

 dition shown in PI. xlvii. fig. 11. The outer part of the nasal-floor 

 cartilage is detached from Jacoljson's cartilage, which is present 

 as an inner plate and an outer bar. In the hollow is found the 

 anterior portion of Jacobson's organ opening directly into the 

 anterior part of the nasal floor, and in no wa}^ directly connected 

 with the naso-palatine canal. It is onl}^ some sections posterior 

 to this, after the organ is quite closed, that the naso-palatine 

 canal unites with the nasal cavity. In other respects the ordinar}' 

 arrangement is followed. 



The relation of the palatine process to the cartilage is more 

 like that found in Petaurus than in Macropus. 



In the early fcetal specimen the vascular and glandular relation 

 of the organ cannot be made out very satisfactorily, but there is 

 apparently nothing remarkable about the organ itself. 



PHASCOLOMYID^. (Plate xlviii). 



Of the Wombat I have only had an opportuning of examining 

 the condition in a half grown specimen, but Rose has fortunately 

 published two very good sections of an early mammary foetus, 

 which I have taken the liberty of reproducing. 



Pkascolomys loomhat, Per. &: Less., (very early foetus, body length 

 19 mm.) [after Rose]. In this early foetus the condition most 

 strikingly resemliles that in the Dasyure. Indeed, if PI. xlviii. fig. 1 

 be compared with PL xli. tig. 3, illustrating the foetal Dasyure, 

 there is not a single feature of importance in which any difiference 

 can be detected. The organ ojiens similarty, the cartilage of 

 Jacobson is similar, the palatine processes exactly agree, and 

 further bear the same relations to the cartilages. PL xlviii. fig. 2, 

 which apparently is a section through the posterior part of the 



