THE 



QUARTERLY JOURNAL 



OF 



THE GEOLOGICAL SOCIETY OF LONDON. 



Vol. XLII. 



1. On the Peemaxillakies and Scalpeifoem Teeth of a large 



extinct Wombat (Phascolohys ctjevieosteis, Ow.). By Sir 



EiCHAED Owen, K.C.B., P.E.S., F.G.S., &c. (Eead November 4, 



1885.) 



[Plate I.] 



Of the fossils discovered in the late exploration of the Wellington 

 bone-caves, casts of a selection have been transmitted to me for 

 determination by the authorities of the Australian Museum, Sydney, 

 New South "Wales. 



I submit a description, with figures, of a specimen showing 

 so much of the premaxillary bones (PI. I. figs. 1-3) as includes 

 the pair of scalpriform incisors (z, ^'). The length of the tooth, 

 following the outer curve, is 160 millim. (6|- inches) ; the trans- 

 verse breadth is 12 millim.; the antero-posterior diameter is 

 10 millim. ; the length of the worn or working surface is 

 26 millim. The major part, if not the whole, of the pulp-cavity, 

 exposed at the back part of the fossil (fig. 3), shows the sharp 

 border of the pulp-cavity, ^', and the chamber which lodged the 

 persistent organ of growth. 



The fore part of the tooth is convex across, the back part 

 feebly so. The implanted portions of the incisors incline towards 

 each other as they approach the hinder open end ; the breadth of the 

 pail', there, is 26 millim. 



The prominence of the outer walls of the socket gradually increases 

 as it approaches the tooth's base, dividing the premaxillary surface 

 into an upper and lower subvertical tract (fig. 1). The under part 

 of the alveolar wall (fig. 2, 22) loses breadth as it recedes from its 



Q. J. G. S. No. 165. B 



