27G 



enamel toward the bottom of the valley and near the basal ridges is punctate; but 

 generally the enamel is smoother and more polished than in Diprotodon. This molar, 

 like the rest of the upper ones, is implanted by two transversely disposed anterior roots 

 (Plato XLIII. fig. 8), and one long transversely extended posterior root. 



The third molar (Plate XLIII. figs. 3 & 4, m i) has its ridges extended rather less ob- 

 liquely than in d t, but more so than in m i of Diprotodon. The antero-posterior diameter 

 is 1 inch 4 lines; the transverse diameter 1 inch 3 lines. As the lobes are more entire 

 they show better the curve of their summits, concave backward. The thicker dnterior 

 basal ridge (/') is continued at both ends upon the corresponding borders of the anterior 

 lobe. The posterior basal ridge (g) is continued internally to the apex of the posterior 

 lobe, gradually subsiding ; externally it curves upon the end of the lobe, and subsides 

 halfway to the summit. 



The fourth molar (Plate XLIII. figs. 3 & 4, m 2 ) shows a diminution of breadth of the 

 hind lobe in a greater degree than the corresponding tooth does in Diprotodon ; its fore- 

 and-aft extent is 1 inch 8 lines. The transverse breadth of the front lobe is, in the old 

 male (fig. 7), 1 inch 7 lines ; in the subject of fig. 4, 1 inch 6 lines ; that of the hind 

 lobe is 1 inch 5 lines. The inner end of each lobe is made thicker by a backward 

 expansion, rather more marked in m 2 than in in 1. 



In the last molar (Plate XLIII. figs. 3 & 4, ma) the slightly abraded summits of the 

 lobes show the more vertical or steeper slope of their fore side, which is convex 

 transversely ; also the transverse concavity of the hind side, due to the seeming backward 

 bend, with thickening, of the outer and inner borders, and the curving slope of the hind 

 (mrt of the lobes, which gives them in profile a slight bend forward (fig. 3, m 3) as in 

 Diprotodon. 



The fore-and-aft extent of this tooth is 1 inch 8 lines ; the breadth of the front lobe 

 is 1 inch 7 lines ; that of the hind lobe is 1 inch 3 lines ; it contracts more rapidly 

 to its summit than in Diprotodon. The posterior root of m 3 is slightly impressed 

 lengthwise at its back part, and deeply so at its fore part. 



The origin of the outstanding zygomatic process of the maxillary terminates poste- 

 riorly opposite, or on a vertical parallel with, the interspace between the third and fourth 

 molars. In one large old Notothere (Plate XLII. fig. 6) it extends, as before observed, 

 a little further back ; in an immature individual its origin hardly extends backward 

 beyond the middle of m 1. This abutment against the upper molar alveoli is strengthened, 

 as the hind molars take more share in the work of mastication. The base of the process 

 stretches forward and upward as far as the parallel with the first alveolus. 



A portion of the left upper maxillary of Nototherium, with d 4, m 1, and m 2, rather 

 more worn than in the above-described specimen, exemplifies the same relation of the 

 base of the malar process of the maxillary with the alveoli of the three anterior molars. 



In not any of the upper molars is the anterior basal ridge (f) so large relatively 

 as in Diprotodon. 



In the upper jaw of Nototherium Mitchelli, in which the last molar had recently 



