270 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 11, 



of its inner bounding ridge shows a triangular fracture immediately 

 under the orifice of the dental canal (at w, fig. 4), where it is com- 

 paratively thick : thence the section becomes gradually attenuated on 

 to the condyle. There can be little doubt that this is the charac- 

 teristic marsupial inflected angle, although feebly developed. It may 

 have formed a slender elongated apophysis, with little inward in- 

 flexion, as in Acrobata. 



The characters of the anterior portion of the inner side of the 

 horizontal ramus, which are concealed by the contact with the matrix 

 in the fragment fig. !,«,&, are beautifully shown by a detached piece 

 lately received from Mr. Beckles, represented by figs. 11-13. It 

 comprises the anterior third of the ramus, the fracture having 

 passed vertically through the middle of the last premolar. The in- 

 cisor is broken oif near the base of the exserted portion ; the two an- 

 terior premolars are quite entire, and show well the diagonal grooving 

 on both sides. The alveolar sheath of the incisor is entire all round, 

 and its upper edge presents an exceedingly abbreviated diasteme. 

 The symphysial portion is very short, directed upwards, massive, and 

 obtuse. The disc of the harmonia or junction between the two man- 

 dibular pieces is distinctly defined (fig. 12, b). It is of comparatively 

 small antero-posterior extent, of a broad elliptical or somewhat reni- 

 form outline, with the sinus directed backwards, and the long axis 

 of the disc with but slight deviation from the vertical. The surface 

 is perfectly smooth and without indentation, as is commonly seen in 

 Hypsi/prymnus and other herbivorous marsupials ; while in the car- 

 nivorous and insectivorous genera of the same subclass, the symphy- 

 sial harmonia is narrower and more elongated, with more or less in- 

 equality of surface for the reciprocal firm apposition of the united 

 pieces. It is of some importance to take due notice of this cha- 

 racter, however trivial it may appear, as every point is of value that 

 can assist us in determining the affinities of this remarkable fossil 

 genus. On the outer surface of this fragment the mentary foramen 

 (fig. 11, c) is seen under the middle of the diasteme. It is round, 

 well defined, and of good size. This instructive fragment furnishes 

 direct evidence upon another point of importance, namely that there 

 was but one large incisor on either side of the lower jaw. 



It would have been of great interest and importance to have ascer- 

 tained the character of the outer surface of the ascending ramus in 

 Flag. Becklesii ; that is to say, whether, in harmony with the mar- 

 supial indications as here interpreted, it presents a depression bounded 

 by a raised ridge sweeping round on the lower side from the condyle 

 to join on with a corresponding ridge descending along the anterior 

 margin of the coronoid ; and whether the depression terminated in a 

 trumpet-shaped excavation of the horizontal ramus, common to it 

 and the dentary canal, as occurs in Hypsiprymnus. But the fossil 

 is so fragile, that I have not attempted to detach it for fear of injuring 

 what it now exhibits. We may expect, however, if the excavations 

 are continued at Purbeck with the same zeal with which they have 

 hitherto been conducted, that abundant materials will be acquired for 

 clearing up this single unascertained point connected with the cha- 



