PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
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part, where the curve becomes deepened posteriorly by the inbending of the angle (a). 
This part gains in thickness as it extends inward ; the inner surface of the part preserved 
in the specimen described is vertical, and in that direction measures 6 lines (fig. 2, a). 
The fractured end (fig. 5, a) shows the three-sided character of this part of the angle, 
the upper and under surfaces converging to the thin horizontal plate (ib. b) connecting 
the angle with the part supporting the coronoid and condyle (ib. d). The fore part or 
beginning of the neck of the condyle may be indicated by the smooth tract (fig. 3, e ), 
which would then define the hind border of the coronoid process ; or this narrow tract 
may indicate a minute transverse perforation of the ascending ramus. On the first notion 
the preserved fore-and-aft extent of the part relating to the support of the condyle ( e , c') 
is 10 lines. 
One may hope ere long to receive a specimen with the whole of the rising branch of 
the mandible complete, showing both the shape and position of the condyle. Seeing 
that in Bettongia (p. 250, fig. 18), Hypsiprymnus (p. 250, fig. 17), Phascolarctos (p. 233, 
fig. 6), and all the marsupial vegetable feeders with a high-placed condyle there is a 
corresponding course of the base of the coronoid from before upward and backward, 
whilst in Tliylacinus (p. 235, fig. 11) and Sarcophilus (p. 235, fig. 12), with a low-placed 
condyle, the base of the coronoid runs straight backward, I take ground for inferring a 
similar or relatively lower position of condyle from the slope of the base of the coronoid 
from before downward and backward, as indicated in the present jaw of Thylacoleo , and 
deem it not improbable that it may have resembled in both respects the Plctgiaulax ; 
thus exemplifying in the form of the mandible, correlatively with the dentition, the 
higher degree of carnivority in these extinct marsupial and diprotodont genera. 
§ 4. Photographs and Cave-specimens of Maxillary Teeth. — Since finishing the descrip- 
tion and figures of the foregoing specimens of maxillary and mandibular structure and 
teeth of the Thylacoleo, I have been favoured by receiving (May 20th, 1870) from the 
Colonial Secretary’s Office, Sydney, New South Wales, a series of Photographs of Fossil 
Remains, and some duplicate specimens, obtained by Dr. A. M. Thomson and Gerard 
Krefft, Esq., from Limestone Caves in Wellington Valley, under the circumstances 
detailed in my paper on Diprotodon , p. 569, Philosophical Transactions, 1870. 
I have subsequently been favoured by the Trustees of the Museum of Natural History, 
Sydney, and the able Curator, Mr. Gerard Krefft, with Photographs, some of them 
duplicates of the above, others of fossils since acquired from the same breccia-caves. 
The Trustees of the Sydney Museum have also transmitted to the British Museum 
duplicate specimens of these cave-fossils. 
From this rich series of photographic illustrations and specimens I select for descrip- 
tion and figures the following, which supplement and almost complete our knowledge 
of the permanent or fully developed dentition of Thylacoleo carnifex. 
The tooth in “Photograph No. 28” (Plate XI. figs. 6, 7) is the anterior incisor, left 
side, upper jaw. It has its crown a little worn at the point ; it is plainly “ canine” in 
function as in shape. The enamelled part of the crown which projects beyond the 
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