312 



PEOFESSOE OWEN ON THE FOSSIL MA31MALS OF AIJSTEALIA. 



rises to a low obtuse point, with a middle longitudinal depression between two con- 

 vexities, on the outside : the inside slopes forvv-ard gradually to the base so as to repre- 

 sent, and act as, a crushing surface. Besides being relatively larger, this ' tubercular ' 

 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 very rare in Felis spelcea. In no 

 Feline does this tooth present the accessory lobe, as in Thylacoleo. In the presence of 

 this lobe at the inner end of the crown, the last small molar in Sarcophiliis presents a 

 closer resemblance to the same tooth in Thylacoleo ; but the principal lobe is more pointed 

 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 affinity of Thylacoleo to Sarcophilus. 



In the Felines the outer wall of the maxillary above the socket of the sectorial tooth 

 is perforated by the large antorbital foramen: it is not so perforated in Thylacoleo. The 

 canal for the suborbital nerve and vessels is relatively smaller in Thylacoleo (Plate XI. 

 fig. 2, c), and must open some way in advance of the socket of the penultimate tooth, as 

 it does in Sarcophilus. From that socket to the orbit the outer surface of the maxillary 

 is smooth and even, first gently concave, then as gently convex: it does not show the 

 zygomatic protuberance which intervenes in Sarcophilus. The vertical extent of this part 

 of the maxillary is 2 inches, being nearly the same as in the Lion. The border of the 

 orbit is sharper and more produced, especially at the loAver and fore part {ih. fig. 1, o'), 

 than in the Lion. 



Sufficient of the palatal part of the maxillary is preserved in this fragment to afford a 

 very significant character of the nature and affinities of the Thylacoleo. In most Marsu- 

 pialia, and in all the carnivorous species, the bony palate is interrupted by large vacuities 

 opposite the antepenultimate and penultimate molars. In all placental Carnivora the 

 bony palate is here entire ; it shows, at least, only a small oblique nervo-vascular foramen 

 at the suture between the palatine and maxillary ; and the roof of the mouth is extended 

 by bone some way behind the last molar tooth. In the present specimen of the Thyla- 

 coleo is preserved the smooth rounded outer border (Plate XI. fig. 2, and Plate XIV. 

 fig. l,d) of a large palatal vacuity opposite the hinder half of the penultimate tooth, and 

 at a distance of 14 lines from it transversely. Such a vacuity extends opposite the 

 penultimate and antepenultimate molar in Sarcophilus (Plate XIV. fig. 2). 



I now proceed with the description of the larger, cranial, portion of the present fossil, 

 before returning to another character in the smaller portion which I regard as decisive 

 of its marsupial affinities. The cranial part of the skull shows a broad and low occipital 

 surface (Plate XV. fig. 1); the sides (Plate XL fig. 1) excavated by large temporal 

 foss£E (27'), with their ridges meeting at a low and short parietal crest (Plate XVL t') ; the 

 upper surface expanding, in front of this, to a very broad, almost flat interorbital region, n. 

 The post-orbital processes, 12, with the zygomatic arches, 2;, and part of the basis cranii, 

 are broken away. The extreme length of this portion of skull is 8 inches ; the least 

 brcadtli of the cranium, at the teni])oral fossa^, is 2 inclies 2 lines. 



