464 



The position of the germ of the last molar is such that the transverse lobes turn 

 their working-edges obliquely inward, rather forward, and, with but a very slight incli- 

 nation, upward, indicating the scmirotating movement by which, in the course of the 

 growth of both tooth and jaw, the crown is brought into the latter direction, and in a 

 working line with the antecedent grinders. The superadded complexities noted in these 

 teeth are multiplied in the last molar; at least so much of the hind surface of the hind 

 lobe as is formed shows, in the left ramus, not fewer than six accessory ridges in the 

 flattened and rather depressed tract included between the hinder terminal ridges or 

 angles of the outer and inner convex ends of the hind lobe. Of these six vertical ridges 

 1 wo are larger than the rest, and of the narrow pyramidal shape before mentioned (they 

 answer to those marked h in fig. 10, Plate XC1V.). 



In the unworn molar of this young jaw (Plate XCV. fig. 6, m i) the mid link does 

 not come to the grinding-surface as in the worn molars from the mandible of the adult 

 Proroptodon (ib. fig. 4) ; they show a sharp concave border slightly notched midway. 

 Notwithstanding some minor differences to be expected in the modifications of the 

 enamel which complicate the crown of the molars in the present genus, the dimensions 

 of d 4, m i, m 2, and m 3 led me to view this mandible as having been derived from a 

 young of Procoptodon Goliah. 



The germ of the premolar was accordingly sought for, and the right ramus (Plate 

 XCV. fig. 7) was fortunately so far preserved as to include its formative cell *. The crown 

 of the tooth therein lodged (ib. fig. 3) has a fore-and-aft extent one third greater than 

 the larger of the two teeth (d s) which it displaces ; the outer side of the crown is divided, 

 as in Procoptodon Papha, by a vertical groove, but more equally ; a short second vertical 

 groove or notch indents the hinder division, near the main groove. The convexity of 

 the exposed part of the crown testifies to the procoptodont character of this premolar. 



The incisors (Plate XCII. fig. 5, i), both broken away near their issue from the alveoli, 

 show a full elliptic section, 6 lines in the vertical, 5 lines in the transverse direction ; 

 they come almost into contact medially ; the transverse extent of the pair is 10 lines; 

 their direction is obliquely forward and upward, as in Nototherium, not procumbent as 

 in the typical Macropodidce. 



The symphysis is continued, broadly, to the incisive outlets ; it has insured, apparently, 

 an attachment to each other of the rami of this instructive mandible, too intimate to be 

 disturbed by posthumous movements, although anchylosis had not been completed, if it 

 had commenced. From the anterior molar to the incisor measures but 10 lines, though 

 it might be 1 inch or a little more if the incisive alveoli were entire. The outlet of the 

 dental canal (ib. fig. 6, v) is small ; it is 3 lines below the diastemal border, and 5 lines 

 from the fore part of the socket of d 2. 



Each ramus is thick vertically, convex externally, in a degree increasing to the origin 

 of the coronoid plate. The thick lower border, where it curves from the horizontal to 



* Permission to remove the requisite portion of bone was accorded by the Museum Committee of the Royal 

 College of Surgeons. 



