84 Proceedings of the Royal Society of Victoria. 



one particular, viz., that in them this bar is connected above 

 and in front with the upper end of Jacobson's cartilage, and 

 below and behind with its lower outer edge. In Petaurus,^ 

 however, and Phalangers,^ and to a less extent in Trichosurus" 

 and Macropods,^ there is a ridge process exactly similar to that 

 of Notoryctes in its origin from the inner upper side of 

 Jacobson's cartilage, becoming detached from it, and then more 

 posteriorly becoming attached to the lower ridge of the cartilage. 

 The " bar " in Notoryctes apparently truly corresponds to that 

 of the other marsupials in that it comes off anteriorly to 

 Jacobson's duct from the ridge process, curls round the Organ 

 and over the duct, and becomes attached posteriorly to tlie duct, 

 to the ventral edge of Jacobson's cartilage, being therefore 

 merely a further exaggeration of what is present in Petaurus, 

 and the Phalangers generally. Meanwhile in Notoryctes, the 

 cartilaginous connection between the palatine processes of the 

 premaxillaries has almost disappeared, the two bones by this time 

 practically fusing. The crescentic character of the bones now 

 harmonises closely with that of the cartilages (Figs. 3 and 4, 

 p. p.p. andyit'.). From the ventral convex surface of the rapidly 

 dwindling cartilage of the outer nasal tloor, is given out just 

 here a small process of hyaline cartilage (Fig. 3, s.c), which is 

 found strengthening the upper and anterior wall of Stenson's 

 duct which lies just posterior to this. Here we have another 

 point of difference from other Marsupials, in which there is no 

 cartilaginous support to the naso-palatine canal, though in 

 Petaurus^ and others we find a process supporting the inner wall. 

 This may also be compared with the Rabbit," in which Stenson's 

 cartilage is a continuation from the cartilage of the nasal floor, 

 and contrasted with the Guinea-pig,^ in which the cartilage 

 forms a closed capsule around the two ducts, and is quite 

 separated from all other cartilages. It is to be noticed here, 

 that the upper horn of the crescentic Jacobson's cartilage is 



1 Proc. Limi. Soc. N.S.W., vol. xi. ii.s., 1896, p. 601, pi. xliv., fijfs. 10, 11. 



2 hoc. cit., p. 616. 



3 Loc. cit, p. 607. 



4 Loc. cit., p. 618. 



5 Broom : Trans. Roy. Soc. Edin., xxxix., p. 240. 



6 Klein : Q.J. M.S., vol. xxi., p. 555. 



7 Loc. cit., p. 228. 



