459 



rough ridge (fig. 1, h), indicative of the lower boundary of the ectocrotaphyte fossa, is 

 at a higher level. 



The ramus gains slightly in depth or vertical extent from the groove (b\ fig. 2) to the 

 symphysis (s, s'). The articular syndesmotic surface is broad, strongly roughened and 

 sculptured, and extends from the lower border of the ramus (s) to the outlet of the 

 incisor (/) ; the hind border of the symphysial surface is feebly impressed, as in Phasco- 

 lomys (Plate LXIII. fig. 2). 



The union of the two rami must have been firm, not admitting of any reciprocal move- 

 ment ; indeed the fore part of the joint had become obliterated by anchylosis, and part 

 of the left ramus is here adherent in the fossil. The inner surface of the ramus is 

 almost flat to where it bends to the under border ; the narrow continuation forward of 

 that surface between the symphysial joint and the diastemal tract (fig. 2, 1, s')is traversed 

 by a ridge, between which and the joint is a narrow groove. The hind part of the 

 ectalveolar groove (fig. 3, u) is deep and moderately wide ; the postalveolar angle (ib. t ) 

 is better marked than in the type Kangaroos. 



The crown of the premolar has been worn or broken off in the original of Plate 

 XCTII. ; the length and breadth of its base are the same as in the undeveloped lower 

 premolar (Plate XC. fig. 6, p 3). The strong fore and hind roots are longitudinally 

 striate. 



The crown of d 4 is worn down to the base ; each lobe shows a broad tract of dentine 

 united by a linear tract along the remains of the mid link. The third tooth (m 1) shows 

 a broad prebasal ridge ; the fore link has been worn down to its base, and the dentine 

 there is continuous with that exposed on the anterior lobe. The tract continued along 

 the mid link to the hind lobe is much narrower, being finely linear. A ridge from 

 the inner side of the link is indicated, and a second ridge from the fore part of the hind 

 lobe internal to the confluence therewith of the link. Indications of the procoptodont 

 sculpturing of the back of the hind lobe are unmistakable, but the pattern is better shown 

 in the succeeding molars ; the outer and inner smooth convex enamelled ends or sides 

 of the hind lobe are continued a short way upon the back of that lobe and terminate 

 there in well-defined borders, between which the surface sinks. This broad, shallow 

 fossa is divided in two by a pyramidal process of enamel in low relief, the basis below 

 being coextensive with the breadth of the fossa, the apex reaching to the working ridge, 

 in its present degree of wear, of the hind lobe of the last molar. 



In the penultimate tooth (m 1) the greater degree of wear gives a strong undulatory 

 course to the enamel-ridge bounding behind the working-surface of the complex molar. 



From what may be discerned, in the cast, of the implanted base and outlet of the 

 socket of the incisor, that tooth was relatively small, as in the subject of Plate XC. 

 fig. 8, and was directed obliquely upward and forward at nearly the same angle as that 

 of the posterior border of the symphysis ; but the cast does not supply safe data for 

 further particulars. 



We have thus in the foregoing evidences of the singular phytophagous Marsupial 



48 



