78 Proceedimjs of the Royal Society of Victoria. 



and partly enclosed by the bony palatine processes of the pre- 

 maxillary bones (the prevoniers of Broom) and by the cartilages 

 of Jacobson. The Organ, with a small ledge of cartilage lying 

 externally to it, causes an elongated triangular projection (Figs. 

 3, 4, 5, i.s.r) on the mesial wall of the nasal furrow, the base of 

 the triangles being formed by the lateral wall of Jacobson's Organ. 

 This ridge in the lining mucous membrane of the nasal furrow, 

 which is always indicative in mammals of the position of this 

 Organ, has been called by Broom "the inferior septal ridge." It 

 is continued in a less degree anteriorly and posteriorly ; anteriorly 

 because of the presence of the cartilaginous shelf supporting the 

 Organ, in front of the Organ itself, the trough so caused being 

 here occupied by glands ; while posteriorly the lower part of the 

 ridge is still present, because of the bony shelf from the palatine 

 processes of the premaxillary bones. Even where the Organ of 

 Jacobson is itself present, the size of its consequent ridge is 

 increased by a considerable development of glandular alveoli, 

 outside Jacobson's cartilage and continuous with the gland masses 

 in front of and behind Jacobson's Organ — compare Phascogale^ 

 Didelphys,'^ Perameles,'^ Pseudochirus.^ 



Cartilages and Bones in connection with the Nasal Organ. 



The cartilaginous nasal septum (Figs. 1 and 2, n.s.c.) is present, 

 dividing the nostrils right up to the anterior end of the snout. 

 Its cartilage is hyaline, and the cells numerous, deeply staining 

 and showing evidence of rapid growth. 



As have others, we find that transverse vertical sections offer 

 the best means of studying this part, aided also by longitudinal 

 vertical sections. Beginning anteriorly, we find that the alinasal 

 cartilage supporting each nostril is well developed, and is free 

 anteriorly on its lower border (Fig. 1, a.c), not being here 

 united to the ventral processes of the septum, but swelling out 

 instead into an edge which is club-shaped in transverse section, 

 and supports a well marked ridge [p.l.r.), the cartilage being 

 covered with a considerable thickness of gland material (m.g.), 

 the whole rendering the cavity of the nostril crescentic in outline. 



1 Broom : Proc. Linn. Soc, N.S.W., vol. xxi., 1W96, p. 593. 



2 Loc. cit., p. 597. 



3 Loc. cit., p. 599-000. 



4 Loc. cit., p. 603. 



