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present gigantic fossil. But the still closer resemblance which the 

 molars of the Tapir bear to those of the Diprotodon calls for further 

 and more decisive evidence before the supposition of its marsupial nature 

 can be entertained witb probability. 



From the alluvial or newer tertiary deposits in the bed of the Conda- 

 mine River, westward of Moreton Bay, Australia. 



Presented by Lient.-Col. Sir Thomas L. Mitchell, C.B. 

 1461. A portion of the left ramus of the lower jaw of apparently the same in- 

 dividual Diprotodon australis ; it includes the two fangs of the last molar 

 teeth and the angle of the jaw. This part more decidedly manifests the 

 marsupial character by its inward inflection, and by the broad flattened 

 surface which the under part of the jaw there presents : this surface forms 

 a right angle with the outer surface of the ramus, the lines of union being 

 rounded off; the outer surface, which is entire to the base of the coronoid 

 process, is slightly concave. The Elephants, Mastodons and tapiroid 

 Pachyderms present the opposite or convex form of the outward surface 

 of the jaw ; the Dinotherium comes nearest, amongst the Pachyderms, to 

 the character of the angle and base of the ascending ramus of the jaw 

 manifested in the present fossil, which, however, in the greater degree of 

 inflection and flattening of the angle, more closely resembles the mar- 

 supial type. The alveolar ridge is continued backwards, for the extent of 

 two inches, in the form of a flattened platform of bone, forming an angle 

 at its inner and posterior extremity. The thin base of the coronoid 

 process extends along the outer border of this platform, and the entry of 

 the dental canal is situated near the posterior end of the base of the coro- 

 noid. The condyloid process and the back part of the jaw ate broken 

 away ; a great part of the thick ridge formed by the inwardly inflected 

 angle of the jaw has also suffered fracture, but about one inch of the 

 middle part of this characteristic structure is entire. The preserved fangs 

 of the last molar show it to have been as large as would comport with 

 the proportions of the molars in the preceding specimen. 



From the alluvial or newer tertiary deposits of the Condamine River, 

 westward of Moreton Bay, Australia. 



Presented by Lieut.- Col. Sir Thomas L. Mitchell, C.B. 



