800 
PROFESSOR OWEN ON THE EOSSIL MAMMALS OE AUSTRALIA. 
In Palorchestes this suture describes a less angular, more semicircular course than in 
existing Kangaroos. The hind border of the bony palate appears to have been more 
concave than in Macropus major or Osphranter robustus , in which respect it resembles 
more some of the Halmaturi. A pair of small vascular foramina, 1 inch 3 lines 
apart, occur at the interval between the right and left premolar (p 3). 
The anterior pier of the zygoma (Plates LXXXII., LXXXIII., 21") is subtrihedal, the 
hind surface or side being the broadest, nearly flat vertically, concave transversely. The 
fore part is subequally divided into an upper and lower facet by a forwardly directed 
rounded angle. A narrow semicircular notch (Plate LXXXI. fig. 1, 0 ) at the upper 
part of the base of this pier indicates a part of an orbit relatively smaller than in the 
Kangaroos. Above and in advance of this notch is the ectorbital aperture of the 
lacrymal canal characteristic of the Marsupialia. There does not appear to be, in 
either side of the skull, a trace of an antorbital foramen ; but I incline to believe in 
some accidental obliteration of that issue, rather than that it never existed. 
Each molar series describes a slight curve convex outward. The base of the broken 
crown of the premolar is subelliptic (Plate LXXXII, fig. 1, p 3 ), 7-g lines in long dia- 
meter, 6 lines in transverse diameter, which is at its middle ; it is not broadest behind 
as in most other Kangaroos ; the inner side is more convex than the outer one. The 
second molar (ib. ib. d 4) is bilophodont, with a prebasal ridge ; a fold of enamel (ib. f) 
indicative of the ridge remains on the inner side ; the rest of the ridge is lost in the con- 
tinuous hollow tract of dentine occupying the base of the worn-down anterior lobe (a). 
Opposite folds of enamel, the inner one the longer, indicate the interlobal valley ; the 
dentine at the base of the link (r) leads across from the anterior to the posterior field 
of attrition. The third molar (ib. ib. m 1) has been worn down to the same degree. In 
both these molars the inner side of the basal part of the front lobe (a) encroaches 
further than that of the hind lobe (b) upon the bony palate, forming the origin of a very 
strong antero-internal root. In the fourth molar (m 2) and in the last (m 3), the corre- 
sponding root makes a projection beyond the inner side of the hind lobe of the tooth in 
advance. The base of the mid link (r) remains in m 2 ; in m 3 that link shows a median 
notch. More of the narrow prebasal ridge (f) is apparent in the last two teeth. The 
hind surface of the penultimate and last molars seems to have been slightly depressed 
at g, fig. 2, but much less so than in Macropus major and Osphranter robustus ; the 
hind lobe of m 3 is narrower than that of m 2. The greatest breadth of the crown of the 
third molar ( m 1) is 10 lines. The surface of the enamel in all the grinders appears to 
be finely rugous. 
Thus, so much of the dental characters as can be defined in the present unique fossil 
concurs with the cranial ones in showing Palorchestes Azael to have deviated less from 
the type of the existing bilophodont Macropodidce than have the species of Procoptodon, 
some of which ( Proc . Goliah , for example) were its rivals in bulk. 
