BY n. BUOOM. 619 



section in Didelphys (PI. xlii. fii;-. 7) it will be seen that the 

 peculiarity is onl}^ due to a sliglit difference in the relative 

 l^osition of the naso-palatine canal In the low position occupied 

 b}' the palatine pi'ocess and the simple condition of the nasal-floor 

 cartilage the Rat-Kangaroo comes considerably nearer the Poly- 

 protodonts than does Macropus. 



The Wombat in its early condition shows a very marked 

 agreement with Dasyurus, and also considerable agreement with 

 -iSlpyprymnus, though the organ opens in the usual way. In the 

 adult the cartilaginous development is on the ty|De of the Macro- 

 pods, though the perfect cartilaginous tube formed b}' Jacobson's 

 cartilage gives it more of the appearance of Phascolarctus. 



Conclusion. 



From the stud}" of this limited region in the snout of the 

 Marsupials we get a number of interesting suggestions in the 

 way of apparent affinities. In the first place there can be little 

 doubt in placing Perameles with Dasyurus and Didelphys and 

 away from the Paalangers, and though it is more differentiated 

 than either it seems to retain certain primitive charactei's lost in 

 the others. The Phalangers are all closely allied, though it would 

 seem that Trichosurus is a little further differentiated than 

 Pseudochirus and Petaurus. Phascolarctus is a much moditied 

 and aberrant form, and it seems probable that a study of the 

 foetus will reveal that it is not so near the Phalangers as has been 

 supposed. The Kangaroo group though allied to the Phalangers 

 is, as regards the r-egion under consideration, nearer the Polypro- 

 todonts; and the Rat-Kangai'oo, though slightly aberrant, helps 

 to bridge over the gap. The Wombat is a very near ally of the 

 primitive or ancestral Macropods apparently, though it has become 

 much modified along an independent line. 



I must acknowledge my indebtedness to Sir William Flower 

 for the specimens of Didelphys examined; to Mr. A. G. Hamilton, 

 of Mt. Kembla, N.S.W., for the young and adult Perameles; and 

 to Prof. Wilson for the permission to examine his sections of the 



