PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
273 
fore-and-aft extent. Fortunately another cranial fragment of the species (Plate XXVII. 
figs. 7, 8, 9) included the premolar and adjoining molar entire, and yielded the required 
subgeneric character of the anterior tooth. The crown is 10 lines in fore-and-aft length, 
5^ lines in vertical extent, 4-| lines across the thickest part of the base, which is near 
the hind end of the tooth. The fore end (figs. 7 & 9, d) is subtrenchant, with a pre- 
hasal 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 concavity 
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 (Plate XXVII. figs. 5 & 6, m i) shows, as in Sthenurus Atlas (Plate 
XXIV. figs. 4-6, m i), a marked increase of size over d 4 . The prebasal ridge is more 
developed ; the exposed dentinal tracts resemble those in Plate XXVII. 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 erubescens) 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). 
