312 
PEOFESSOE OWEN ON THE FOSSIL ]VLLM3L1LS OF ALSTEALIA. 
rises to a low obtuse point, with a middle longitudinal depression between two con- 
vexities, on the outside: the inside slopes forward gradually to the base so as to repre- 
sent, ah act as, a crushing surface. Besides being relatirely larger, this « tuberciUar 
tooth is more deeply and firmly implanted than in the Lion, whence is due its preserva- 
tion in the present fossil, a circumstance which is 1017 rare in Felts spelm. In no 
FeUne does this tooth present the accessory lobe, as in Thylacoleo. In the presence ot 
this lobe at the inner end of the crown, the last small molar m SarcopMus presents a 
closer resemblance to the same tooth in ThjUcoleo ; but the principal lobe is more pomted 
and trenchant in the small existing marsupial carnivore; and the whole tooth is so 
situated that its outer end is visible in a side view. The firm implantation of the last 
small molar, and its shape, are significant of the afiinity of Thylacoleo to Sweophhts. 
In the Felines the outer wall of the maxillary above the socket of the sectonal toot 
is perforated by the large antorbital foramen : it is not so perfomted in Thylacoleo. 
canal for the suborbital nerve and vessels is relatively smaller 111 Thylacoleo (Plate . . 
fig 2, c), and must open some way in advance of the socket of the penultimate toot , as 
it does in SarcopMlus. From that socket to the orbit the outer surface of the maxillary 
is smooth and even, fii'st gently concave, then as gently convex: it does not show e 
zyciomatic protuberance which intervenes in Sarcophilus. The vertical extent of this part 
oirfhe maxillary is 2 inches, being nearly the same as in the Lion. The border ot tne 
orbit is sharper and more produced, especially at the lower and fore part {tk fig. . 0). 
tliciii lu tbc Lion. ^ p . aVvt 1 o 
Sufiicient of the palatal part of the maxillary is preserved m this fragment to afloi . 
very significant character of the nature and affinities of the Thylacoleo. In most Marsif 
malia. and in all the carnivorous species, the bony palate is interrupted by large vacuities 
opposite the antepenultimate and penultimate molars. In all placental Cainhoia t n 
bony palate is here entire ; it shows, at least, only a small oblique nervo-vascular toranien 
at tL suture between the palatine and maxillary ; and the roof of the mouth is extenued 
by bone some way behind the last molar tooth. In the present specimen ot the Thy.a- 
coleo is preserved the smooth rounded outer border (Plate XI. fig. and 1 late X . 
fig 1, d) of a large palatal vacuity opposite the hinder halt of the penultimate toot 1, am 
at a distance of 14 lines from it tmnsversely. Such a vacuity extends opposite tlie 
penultimate and antepenultimate molar in Sarcophthts (Plate Xll . fig. 
I now proceed with the description of the larger, cranial, portion ot the present tosal. 
before returning to another character in the smaller portion which I reganl as deasiie 
of its marsupial affinities. The cranial part of the skull shows a broad and low occipiM 
surface (Plate XV. fig. 1 ); the sides (Plate XL fig. 1 ) 
fossae (27'), with their ridges meetmg at a low and short parietal ciest (I late X . 
upper surface expanding, in front of this, to a very broad, almost flat interoibital region. 
The post-orbital processes, with the zygomatic arches, and part of the basis cm.m 
fie broken away The extreme length of this portion of skull is 8 inches; the least 
breadth of the cranium, at the temporal fosstn, is 2 inches lines. 
