80 Proceedings of the Royal Society of Victoria. 



contrasted with the condition found in most Marsupials, and also 

 in Rodents, in which they are at most in contact with the nasal 

 septum. In the Macropodidae, Symington^ has noted the con- 

 nection of the nasal floor cartilages to the ventral edge of the 

 nasal septum, by perichondrium. 



Beneath this, and separated from the cartilage by connective 

 tissue and blood-vessels, are the extreme anterior ends of the 

 premaxillary bones {p.b ), just losing their fibrous cartilaginous 

 connections with the lateral edges of the nasal floor, and 

 separated from each other in the middle line by a large vein (v.). 

 Above this vein is a somewhat wedge-shaped nodule of hyaline 

 cartilage {p-c), which in the next section posteriorly sends down 

 a fibrous process to occupy the space between the two premaxil- 

 laries, pushing the vein ventralwards. In this section, also, 

 the nasal bones (n.l>.) have grown down, enclosing the alinasal 

 cartilages nearly to the level of the primary ridge, and three 

 sections further back the nasal and upward processes of the 

 premaxillary bones meet, completing the bony as well as the 

 cartilaginous capsules round the nose. Still proceeding back- 

 wards, we find that the wedge-shaped cartilage has now com- 

 pletely descended between the premaxillaries to form the 

 connection between their mesial edges. The above description 

 can be readily corroborated on reference to longitudinal sections. 

 Splitting off anteriorly from the ventral edge of the septum is the 

 narrow sheet of fibrous cartilage passing obliquely downwards 

 and backwards to lie between the palatal processes of the pre- 

 maxillary bones in their anterior part. On the hinder face of 

 this sheet of cartilage is the hyaline cartilaginous swelling, which 

 in transverse section appears wedge-shaped. In front of the 

 sheet, the bones are separated by a well-defined vein, connected 

 with a large blood sinus, which curves round vertically in front 

 of the cartilaginous septum. Posteriorly in these longitudinal 

 sections we can see that the central cartilaginous bar or 

 narrow sheet becomes lost as the two palatal processes 

 of the premaxillae become more intimately united. There 

 can be, I think, no doubt but that this central cartilage repre- 

 sents here the prenasal cartilage of other animals. Its general 



1 Jour. Anat. and Phys., vol. 26, p. 372, and pi. x., fig. 1. 



