796 
PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
In the unworn molar of this young jaw (Plate LXXX. fig. 6 , m 1 ) the mid link does 
not come to the grinding-surface as in the worn molars from the mandible of the adult 
Procoptodon (ib. fig. 4) ; they show a sharp concave border slightly notched midway. 
Notwithstanding some minor differences to be expected in the modifications of the 
enamel which complicate the crown of the molars in the present genus, the dimensions 
of d 4 , m i, m 2, and m 3 led me to view this mandible as having been derived from a 
young of Procoptodon Goliah. 
The germ of the premolar was accordingly sought for, and the right ramus (Plate 
LXXX. fig. 7 ) was fortunately so far preserved as to include its formative cell *. The crown 
of the tooth therein lodged (ib. fig. 3) has a fore-and-aft extent one third greater than 
the larger of the two teeth (^ 3 ) which it displaces ; the outer side of the crown is divided, 
as in Procoptodon Papha, by a vertical groove, but more equally ; a short second vertical 
groove or notch indents the hinder division, near the main groove. The convexity of 
the exposed part of the crown testifies to the procoptodont character of this premolar. 
The incisors, both broken away near their issue from the alveoli, show a full elliptic 
section, 6 lines in the vertical, 5 lines in the transverse direction ; they come almost 
into contact medially ; the transverse extent of the pair is 10 lines; their direction is 
obliquely forward and upward, as in Nototherium , not procumbent as in the typical 
Macropodidce. 
The symphysis is continued, broadly, to the incisive outlets ; it has insured, apparently, 
an attachment to each other of the rami of this instructive mandible, too intimate to be 
disturbed by posthumous movements, although anchylosis had not been completed, if it 
had commenced. Prom the anterior molar to the incisor measures but 1 0 lines, though 
it might be 1 inch or a little more if the incisive alveoli were entire. The outlet of the 
dental canal (ib. fig. 6 , v ) is small ; it is 3 lines below the diastemal border, and 5 lines 
from the fore part of the socket of d 2. 
Each ramus is thick vertically, convex externally, in a degree increasing to the origin 
of the coronoid plate. The thick lower border, where it curves from the horizontal to 
the ascending parts of the ramus, is slightly inflected ; a rather wide shallow groove 
extends above it. The inner surface of the ramus in advance of the inflection is feebly 
convex vertically. The base of the coronoid process describes a curve convex inward as 
it extends from before backward. 
The lower border of the left ramus is entire from below (m 1 ) backward to the hind 
fracture ; it is obtuse. The thickness or transverse diameter of the ramus, below the 
middle of m 3, is rather more than four fifths the vertical diameter at that part. Thus 
the characters of the mandible of the smaller species of Procoptodon are closely repeated 
in that of the immature specimen of the larger species. 
If the present mandible of Procoptodon Goliah be compared with that of Nototherium 
Mitchelli in a like state of preservation, which is the subject of Plate iv. Philosophical 
* Permission to remove the requisite portion of bone was accorded by the Museum Committee of the Royal 
College of Surgeons. 
