II.] 



PALEONTOLOGY OF MARSUPIALS. 



53 



than the other two, while there are minute additional cusps at the 

 two extremities, and a distinct ledge at the base of the inner side 



Nat. size. 



FIG. 7. IMPERFECT RAMUS OF LOWER JAW OF Phascolotherium. 



of each tooth. In the allied Amphilestes, from the same forma- 

 tion, of which the imperfect lower jaw is shown in the annexed 

 figure, the molars are of the same general type as in the preceding, 

 but much more numerous, their total number being probably 

 nearly the same as in the next genus. 



Nat. size. 



FIG. 8. IMPERFECT RAMUS OF LOWER JAW OF Amphilestes. 



Another type is represented by the genera Amphitherium of 

 the Stonesfield Slate and Amblotherium of the upper Jurassic of 

 Dorsetshire, in which, in addition to the canines, there are from 

 six to eight molar teeth, four premolars, and four incisors in each 

 half of the lower jaw. The lower molars differ from those of the 

 preceding genera, and thereby resemble the corresponding teeth 



