PEOFESSOE OWEN ON THE FOSSIL MAMMALS OF AUSTEALIA. 
791 
that surface between the symphysial joint and the diastemal tract (fig. 2, l , s') is traversed 
by a ridge, between which and the joint is a narrow groove. The hind part of the 
ectalveolar groove (fig. 3, u) is deep and moderately wide ; the postal veolar angle (ib. t) 
is better marked than in the type Kangaroos. 
The crown of the premolar has been worn or broken off in the original of Plate 
LXXYIII. ; the length and breadth of its base are the same as in the undeveloped 
lower premolar (Plate LXXVII. fig. 6, p s). The strong fore and hind roots are longi- 
tudinally striate. 
The crown of d 4 is worn down to the base ; each lobe shows a broad tract of dentine 
united by a linear tract along the remains of the mid link. The third tooth (m i) shows 
a broad prebasal ridge ; the fore link has been worn down to its base, and the dentine 
there is continuous with that exposed on the anterior lobe. The tract continued along 
the mid link to the hind lobe is much narrower, being finely linear. A ridge from 
the inner side of the link is indicated, and a second ridge from the fore part of the hind 
lobe internal to the confluence therewith of the link. Indications of the procoptodont 
sculpturing of the back of the hind lobe are unmistakable, but the pattern is better shown 
in the succeeding molars ; the outer and inner smooth convex enamelled ends or sides 
of the hind lobe are continued a short way upon the back of that lobe and terminate 
there in well-defined borders, between which the surface sinks. This broad, shallow 
fossa is divided in two by a pyramidal process of enamel in low relief, the basis below 
being coextensive with the breadth of the fossa, the apex reaching to the working ridge, 
in its present degree of wear, of the hind lobe of the last molar. 
In the penultimate tooth (m 2 ) the greater degree of wear gives a strong undulatory 
course to the enamel-ridge bounding behind the working-surface of the complex molar. 
From what may be discerned, in the cast, of the implanted base and outlet of the 
socket of the incisor, that tooth was relatively small, as in the subject of Plate LXXVII. 
fig. 8, and was directed obliquely upward and forward at nearly the same angle as that 
of the posterior border of the symphysis ; but the cast does not supply safe data for 
further particulars. 
We have thus in the foregoing evidences of the singular phytophagous Marsupial 
genus, with the dentition, as to the formula and fundamental pattern of the molars, of 
the bilophodont Macropodidce, the extremest deviation from the characters of the existing 
subgenera which the fossil remains of the family have yet exhibited. 
I infer from the proportions and shape of the mandible that the rest of the skeleton 
may have presented a more robust character, with thicker and shorter extremities and 
with less inequality between the fore and hind pairs of limbs than in the living Kanga- 
roos. Of these, as before remarked, Procoptodon Pusio must have exceeded in bulk 
the largest known. This excess is greater in Procoptodon Bapha. But the following 
fossils show that their generic modifications have been exemplified on a more gigantic 
scale. 
§ 8. Procoptodon Goliah , Ow. — The present extinct species of Macropodidce was 
mdccclxxiv. 5 0 
