DIPROTODON. 395 



that of the Wombat, as to encourage me to indicate the former 

 existence of a Marsupial apparently as large as a Rhinoceros, and 

 for which I proposed the provisional generic name of Diprotodon,{\.) 

 ranking it with the Wombat in the family ' PhascolomyidcB,\2) I have 

 subsequently obtained further evidence of the marsupial nature of 

 the Diprotodon in the inflected angle of the lower jaw, and of its 

 affinities to the Phascolomys in the form and extent of the symphysis 

 of the jaw, and in the peculiar construction of the os calcis ;(3) but 

 at the same time, with proof that these characters of Phascolomys 

 were combined with molar teeth shaped like those in the genus 

 Macropus. The great incisive tusk (4) extends forwards and slightly 

 upwards, its socket being close to the symphysis in each ramus 

 of the lower jaw ; it is sub-compressed, measuring in one specimen, 

 an inch and a half in vertical diameter, and nearly one inch in 

 transverse diameter ; in another specimen the same admeasurements 

 giving respectively one inch two lines and ten lines. This incisor 

 has a partial covering of enamel, which is laid upon its lower and 

 a considerable part of its outer surfaces ; the whole being invested 

 by cement which is thickest on the upper and inner surfaces of the 

 dentine, where there is no enamel. In three specimens of this 

 tusk from the different localities of Wellington Valley, Moreton 

 Bay, and the district of Melbourne, the protruded extremity had 

 been broken off"; but this may be concluded to have been chisel-shaped 

 from the partial deposition of the dense enamel. 



The molar teeth(5) are five in number in each ramus of the 

 lower jaw, as in the Wombat ; but they are implanted each by two 

 fangs, and the crown is divided into two principal transverse wedge- 

 shaped eminences, with an anterior and posterior basal ridge or 

 talon. The two principal eminences are shghtly curved, with the 

 concavity directed forwards : they are higher and more compressed 

 from behind forwards than in the Kangaroo, Dinothere, Tapir, or 

 Manatee, which present the same type of molar tooth ; and there 



(1) Mitchell's Expeditions into Australia, 1838, vol. ii, p. 362, PI. 31, figs. 1 and 2. 



(2) * On the Classification of the Marsupialia,' Zoological Transactions, vol. ii, p. 332. 



(3) See the Catalogue of the Fossil Mammalia in the Museum of the Royal College of 

 Surgeons, pp. 294, 303. 



(4) PI. 90, fig. 1, i. (5) PL 90, fig 1, m m. 



