PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
53 
by which the lower border graduates into the hind one of the rising branch : the curve 
changes slightly on rising to the level of the alveoli, being then feebly concave above 
the anterior inflected part of the lower margin ; it becomes convex where the border is 
again inflected, and above this the hind border of the ascending ramus, after contracting, 
expands transversely, apparently to support the condyle. The angle or anterior inflection 
( d , d) is but slightly bent inward, with a thick and smooth border ; the longitudinal extent 
of this inflected part is about 4^ inches, closely repeating, as far as it is preserved, the 
characters of the more perfectly preserved angle of the type specimen (Cut, fig. 1, d, d)*. 
An oblique longitudinal wide and shallow channel intervenes on the inner side of the 
ramus between the inflection (Plate IV. fig. 1, d, d) and the low tuberous termination f 
of the postalveolar ridge (ib. & fig. 2, t), about an inch and a half behind the socket 
of the last molar (m 3). This channel is continued backward with a partial interruption, 
caused by the forward extension of the inflected angle or hind border of the ascending- 
ramus (Plate IV. fig. 2, a , e). This part is broken away in the type specimen. 
In no part of the oblique channel (ib. b) occupying and mainly forming the inner 
surface of the ascending ramus of the jaw is there any trace of inlet of a dentary canal ; 
in this respect, as in the somewhat unusual position of that inlet or entry, the present 
mandible agrees with the type fragment J. Some nerve or vessel has left its impress 
along the middle of the channel, but has quitted it for contiguous soft parts without 
penetrating the bone. 
The outer surface of the ascending ramus rises from the line of the anterior inflection 
( d ) with a feeble vertical concavity, speedily changed to a convexity curving outward to 
the thick obtuse lower boundary (Plate II. & Plate IV. fig. 1, h) of the ectocrotaphyte 
depression (ib. f). The fore part of this depression is formed by the corresponding part 
of the rising ramus (ib. and fig. 2, </), which commences opposite the hind part of the 
last molar (m 3), and at a distance outside it of 1 inch 3 lines. The base of the “ coro- 
noid” plate (Plate IV. fig. 2, q, Ji) describes a curve, concave outward, of which base an 
extent of 5 inches (in a straight line) is preserved. The process is broken off in both 
rami; it was thickest at the fore part of its base (Plate IV. fig. 4, q), which here gives 
half an inch. The dental nerves and vessels groove the inner and back part of the base 
of the coronoid before penetrating it obliquely in the same position (at 0 , figs. 1 & 2) as 
that in the types pecimen (Cut, 1, 0). 
Between the postinternal alveolar process (Plate IV. figs. 1, 2, t) and the base of 
the coronoid process, is an irregular shallow channel (ib. u ), narrowing as it passes back- 
ward to the dental canal ( 0 ). The depth of the mandibular ramus at the back of the 
last tooth-socket is 4 inches, the thickness of the ramus at the fore part of the origin of 
the coronoid process is 2 inches 6 lines. 
The interspace between the right and left last socket is 3 inches 6 lines. The breadth 
of the mandible, taken anterior to the origin of the coronoid process, is 7 inches 8 lines ; 
whence the jaw gradually expands to the condyles. We may estimate its breadth at the 
* Op. cit. pi. 4. figs. 3 & 5, a. f Loc. cit. figs. 2 & 3, b. 
J Loc. cit. fig, 
