236 THE BATH OOLITE PERIOD. CHAP. 



on each side. The njolars are essentially tricuspid, with accessory 

 smaller cusps on the inner edge ; their surface I find to be minutely 

 undulated with a sort of shagreen pattern, which does not appear 

 in the teeth of the other genus. 



(A, 



Diagram LXXXII. Interior aspect of lower jaw, referred to Phascolotherium 

 Bucklandi, and magnified tooth to shew the quinquecuspid character more clearly 

 than usual. The surface is distinctly ' chagrined,' with little approximate irregular 

 pits. Natural size. Specimen in the collection of Mr. J. Parker. 



Compared with the ordinary didelphys of Virginia, the corre- 

 spondence is very obvious : similar teeth in the same number and 

 general proportion. Still more close, in the opinion of Owen, is the 

 alliance with thylacinus, a much larger marsupial of Australia; and 

 thus we are conducted to the easy recognition of a second primaeval 

 genus of that now restricted family of quadrupeds. 



STEREOGNATHUS. 



Stereognathus ooliticus is the title of a fragment of lower jaw, 

 which was made known by Mr. Charlesworth, as in the possession 

 of the Rev. J. Dennis of Bury e . ' The specimen was part of the 

 centre of one branch of the lower jaw ; its curvature was very slight, 

 and the concavity below. The section where it was broken across 

 was rectangular, and as wide as deep. The surface presented no 

 trace of suture or vascular lines. Three teeth remained, occupying 

 half the length of the fragment, and one of these had six similar 

 cusps arranged in two rows/ 



The drawing of this little fossil (Diagram LXXXIIL), made by 

 l 2 



Diagram LXXXIIL Stereognathus ooliticus. Natural size. 



Mr. Bone, under the direction of Professor Huxley, represents three 

 teeth in a fragment of the lower jaw, which is convex externally, 



e Keport of the Liverpool Meeting of the British Association, 1854. 



