425 



the hind end of the tooth. The fore end (Plate LXXXVIL figs. 7 & 9, d) is subtrenchant, 

 with a prebasal triangular prominence, one angle subsiding halfway along the trenchant 

 fore border. The middle two thirds of the outer surface (fig. 7, a) show the usual con- 

 cavity lengthwise between the smooth and prominent fore (d) and hind (e) ends of the 

 crown, and on this depressed surface are three vertical obtuse ridges, dividing four shallow 

 linear grooves. The cutting-edge (a) similarly sinks below the angular summits of the 

 terminal prominences (d, e). On the inner side of the crown may first be noticed a low 

 narrow ridge (fig. 8,f), extending a few lines backward from the inner basal angle of 

 the prebasal prominence. Above the ridge (f) begins the broader rising, which soon 

 stands out as a low inner basal division of the crown ; it bends up posteriorly to abut 

 against the inner side of the hind expansion (e), leaving a small triangular depression 

 between the buttress and the hind margin of the tooth. The interval between the inner 

 basal lobe or ridge (b) and the outer or main part of the tooth is less depressed than 

 in Sthenurus Atlas, and does not show the small transverse connecting bars in the hollow. 

 Masticatory attrition has polished the inner side of the blade or outer main part of the 

 crown of this premolar and the inner basal prominence, indicative of a corresponding 

 transverse extension of the crown of the lower premolar. A speck of dentine has been 

 exposed on the buttress. As compared with the upper premolar of Sthenurus Atlas, 

 the generic pattern is closely retained, but with the specific modifications above defined. 



The crown of the adjoining molar (d 4, fig. 9) is worn obliquely from without nearer 

 to the base of the inner side of the tooth. The very narrow prebasal ridge is shown. 

 The dentine exposed on each lobe is broadest at the inner half of the grinding-surface, 

 and it extends in both lobes into an angular form behind, that of the fore lobe indi- 

 cating the rudimental link, that on the hind lobe the rudimental postbasal ridge. 



The third tooth (ib. figs. 5 & 6, m i) shows, as in Sthenurus Atlas (Plate LXXXIV. 

 figs. 4-6, m i), a marked increase of size over d 4. The prebasal ridge is more deve- 

 loped ; the exposed dentinal tracts resemble those in Plate LXXXVIL fig. 9, d 4, but 

 are rather less extensive. The characters of the slightly worn penultimate and last 

 grinders have already been defined, and are sufficiently given in figs. 5 & 6, m 2, m 3. 



The hind border of the bony palate is so entire in the present evidence of Sthenurus 

 Brehus as to show that it described a moderate unbroken concave curve, as in Osphranter 

 robustus. So much of the palate itself as is preserved suffices to exemplify its corre- 

 spondence with that and other larger existing Kangaroos {Macropus major, Macropus 

 rufus, Phascolagus eruhescens) in the degree of its integrity. 



The masseteric process descends opposite the hind lobe of the penultimate molar, and 

 the hind margin of the anterior zygomatic pier is opposite the fore part of the fore lobe 

 of the last molar (ib. fig. 6, m 3). 



The extent of the alveolar part of the maxillary in advance of the masseteric process 

 is relatively greater than in Macropus major, and more resembles that in the Kangaroos 

 which longer retain the premolar and which have that tooth of larger relative dimen- 

 sions than in the type of Macropus proper. The amount of fracture and variety of 



