458 



end gives an ovoid section 5i lines in vertical, 3 lines in transverse diameter ; the outer 

 side is moderately convex, the inner side less so: botli upper and lower borders are thick 

 and obtuse; a thin coat of enamel extends from the lower upon the outer sides of the 

 tooth. The shape of the working crown cannot be inferred from the basal part here 

 preserved ; but this shows faint longitudinal broad impressions on the outer side, and 

 also that the incisor must have risen obliquely upward at a low angle (140°) with the 

 horizontal line of the molar series. 



Thus the present, like the following evidence of the genus Procoptodon, indicates, 

 with the shortness and depth of the symphysial part of the jaw, the thickness of the 

 crown of the lower premolar especially behind, and the thickness and apparent depth 

 of the ramus, a nearer approach to the characters of Nototherium than is shown in 

 any of the foregoing extinct genera of the Macropodal group of Marsupialia. 



What is wanting in the above-described fragment of jaw with the small proportion 

 of dentition, by which is indicated a second species of Procoptodon, has been supplied 

 by a plaster cast and photographs of an almost entire right ramus, with the molar series. 

 The complex characters of the hindmost and least worn teeth (Plate XCIII. fig. 3, 

 m a, m 3) unmistakably repeat the generic type of those of the upper molars of Procop- 

 todon Pusio (Plate XC. fig. 7) ; but the difference of dimension is, to my experience, 

 specific ; and since it is in degree that shown by the premolar germ in the fragment 

 of immature jaw (Plate XC. fig. 8), I regard the specimen in the Sydney Museum, 

 from which the cast and photographs were taken, as part of a mandible of a mature 

 individual of Procoptodon Rapha. The longitudinal extent of the upper molars (d *-m 3) 

 in Proc. Pusio is 2 inches 6 lines ; that of their homotypes in the mandible of Proc. 

 Rapha is 3 inches. The breadth of these lower molars similarly exceeds that of the 

 upper ones in the subjects of Plate XC. figs. 6, 7, which is fatal to the hypothesis of 

 those of Plate XCIII. belonging to the same species. 



The mandibular ramus of Procoptodon Rapha is short, straight, deep, and thick ; in 

 the latter dimension (fig. 3) increasing from the symphysis to the ascending branch 

 more gradually but to a greater extent than in preceding genera of Kangaroos. The 

 lower border is convex across, thickest behind the symphysis, and suddenly becomes 

 thinner at its hinder third (ib. fig. 2, d, d'), where a longitudinal channel (ib. V) along 

 its inner side gives it the appearance of being slightly inflected that way ; but the 

 channel (b 1 ) is interrupted by a more sudden or direct inflection of the proper " angle of 

 the jaw" (ib. a), which here, as in the other macropodal fossils, has been broken away. 



The fore border of the symphysial end of the ramus bends up at about an angle of 

 135° with the axis of the mandible. On the outer side (ib. fig. 1) the alveolar tract is 

 impressed by an irregular longitudinal moderately deep channel, below which the bone 

 swells out and the vertical convexity to the lower border augments from below the 

 first molar (p 3) to the origin of the coronoid process (q). A little way behind the ante- 

 rior border of this process it is feebly impressed, or the surface subsides; but the low 



