74 
PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
ventured on in the figures of these fossils * was verified by the molars in the immature 
jaw subsequently sent by Leichhardt. The first complete penultimate molar which I 
had the opportunity of studying showed the base of the crown girt by a “ cingulum,” 
developed behind into a low talon, and interrupted at the outer end and more so at 
the inner end of the two main lobes, and for a greater extent at the inner than at the 
outer sides : this character my present series shows to be constant. 
The horizontal contour of the crown of the penultimate molar is rather rhomboidal 
than quadrate ; for the hind lobe is more internal in position than the front one, and 
the ridges run, not in a line directly across the alveolar border, but from without inward 
and a little backward. The fore part of the outer end of each ridge is a little produced, 
most so in the hinder one, in which the produced part inclining inward, terminates or 
abuts below upon the middle of the base of the front ridge : the anterior part of the 
inner end of each ridge is a little produced forward, in an angular form ; the general 
result is that the summit of each ridge is slightly concave forward, convex backward. 
The enamel is for the most part smooth and polished ; the delicate strise of growth 
are well marked when viewed by a pocket-lens on the outer side of the tooth, and the 
same power brings into view a few punctations on the hinder slope of each ridge : the 
enamel is rather thicker on this slope than on the front one, and seems more so from 
being more obliquely abraded from before downward and backward : so exposed, the 
coronal surface of the enamel is a line in thickness ; the tract of dentine abraded in the 
present tooth is two lines across. The hinder talon, or part of the cingulum, is most 
developed ; the front one seems as if destroyed by pressure of that of the preceding 
molar. 
Much of the crown of the last molar (ib. m 3) has been broken away ; its base measures, 
in fore-and-aft extent 1 inch 10 lines, in transverse extent 1 inch 3^ lines; this is at the 
anterior lobe, the posterior one is narrower. Each fang is longitudinally excavated at 
the surfaces next each other ; and the outer part of the root, so defined, is thicker than 
the inner part. 
The next stage of dentition which I have had the opportunity of observing in an 
original specimen of the present species corresponds with that of the maxillary teeth 
in the skull (Plate III. fig. 3) ; it is exemplified in the mandible which is the subject of 
Plate IV. The crown of the last molar (Plate X. figs. 1 & 2, m 3 ) is worn to within 
three or four lines of the transverse valley ; those of the penultimate (m 2 ) and antepe- 
nultimate (m 1 ) molars show increasing degrees of attrition : the first and second molars 
are gone, but their sockets remain in the left ramus : the crowns are restored in outline, 
in fig. 1, from the subject of Plate VI. 
The anterior fang of the first molar remains in the corresponding division of its 
socket : the fore-and-aft extent of the socket is 1 inch, being 3 lines more than in the 
young specimen (Plate VI. figs. 1 to 5, d 3 ). Now, as the roots of the first molar in that 
specimen are hollow shells of bone widening to their open base, the crown of the tooth 
* “ On the Extinct Mammals of Australia,” Reports of Brit. Assoc, for 1844, p. 231, plate 3. fig. 1. 
