330 



1788. The skull of a young male of the same species of Potoroo. 



The last molars are in place on each side of the upper jaw, and the deciduous molars being 

 still retained, the series of grinders includes six teeth : the progress of dentition is more tardy 

 in the lower jaw. 



Presented by Governor Sir George Grey, C.B. 



1789. The skull of a young male of the same species of Potoroo. 



The last true molars are completely in place, and the deciduous molars are retained : so 

 that the dental formula seems to he, ~, c ^, p |^|, m = 34. The crowns of the per- 

 manent premolars of the right side are exposed in both upper and lower jaws. The skull is 

 mutilated behind. 



Presented by George Bennett, Esq., F.L.S. 



1790. The skull of a younger individual of the same species of Potoroo. 



The dentition consists of the permanent incisors and canines, the deciduous molars, and 

 the first permanent true molar : it corresponds with that of the young Kangaroo (No. 1728), 

 but differs in the complete acquisition of the third or outer incisors of the upper jaw, as well 

 as of the canines. 



Presented by George, Bennett, Esq., F.L.S. 



1791. The ossa innominata, with one of the marsupial bones, of a young Hypsi- 

 prymnus myosurus. 



It shows a small additional ossicle contributing to the acetabulum, and excluding the pubis 

 from any share therein. 



Presented by Prof. Owen, F.R.S. 



, Tribe RHIZOPHAGA. 



Genus Phascolomys. 



1792. The skeleton of the Wombat (Phascolomys Vombatus). 



The seventh (last) cervical vertebra is perforated by the vertebral artery : 1 5 vertebrae bear 

 ribs, the first six of which articulate directly with the sternum, and the remaining nine inter- 

 mediately. The twenty-third vertebra from the skull bears a short flattened and horizon- 

 tally expanded pleurapophysis, which is suturally articulated to it ; inclusive of this there 

 are 4 lumbar vertebrae : 4 vertebrae have partially coalesced into a sacrum, but two only of 

 these abut against the ilia. There are 10 caudal vertebrae, none of which have hcemapo- 

 physes. The haemapophysial part of the atlas is not ossified, and the wide interspace of the 

 neurapophyses below is filled by ligamentous substance, upon which the true body of the 

 atlas, here forming a strong odontoid process, rests. The metapophysis rises suddenly from 

 the outside of the prozygapophysis of the twelfth dorsal, increases in length to the second 

 lumbar, diminishes by degrees to the second sacral, and is rudimental in the following sacral 



