ON AN EXTINCT GENUS OF THE MARSUPIALS 

 ALLIED TO HYPSIPRYMNODON. 



By C. W. De Vis, M.A. 



Plate I. 



A somewhat obscure passage in the older writing on the 

 palimpsest of the Marsupials has lately been brought to light by 

 Mr. R. Frost, a gentleman who, by such success in this his first 

 search among the archives of King's Creek, will doubtless be led 

 to further discovery. A jaw of no mean size, it appeared, when 

 seen by the writer on the spot, to have been derived from a 

 gigantic Hyspiprymnodon, and this first impression, though con- 

 siderably modified, has not been removed by subsequent study. 



Its functional dentition is that of the Phalangistidte and Pleo- 

 podidje, i-c-pm''-m^-m--m^-m* ^^^ ^he formula is not a full expression 

 of its afiinities. For convenience, and for the sake of brevity, 

 these may be named as they appear in the course of description. 



Jaw. — The fossil is a left horizontal ramus, perfect above to the 

 base of the coronoid process inclu.sive, below to the parallel of ni'*. 

 The molars being in horizontal position, the symphysis makes with 

 them a very low angle (Ifypsiprymnodon); its articulating surface 

 commences anteriorly close to the incisive outlet, and, though long 

 as well as deep, does not extend backwards beyond the vertical of 

 the premolar (I/ypsiprymnodon) ; immediately behind it is a distinct 

 postsymphy.sial depression, and behind this again the jaw swnlls 

 out and forms a prominent internal angle (I/ypsiprymnodon, JIj/p- 

 Hiprymnus occasionally). The incisive region is greatly produced, 

 its length covering three and a-half of the molars {Ilypsiprym- 

 nodon). The unU-rior half of the diastema) edge is occupied by 

 the convex Hut)tul)ul!ii- socket of the procumbent canine, the 

 convexity and breadtli of tlie socket decreasing, till it merges into 



