PROFESSOR OWEN ON THE AFFINITIES OF THYLACOLEO. 
581 
fig. 1 , p 4 ) : nest, the relative extent and depth of the depression (d) for the insertion of 
the temporal, or great biting, muscle. The outline of the termination of the coronoid 
process (b) is given on the authority of Mr. Ramsay, from other and fragmentary 
portions of Thylacolean mandibles. The upper border of the process extends back¬ 
ward at a more open angle than in the Potoroo or Koala (ib., fig. 3), and to an extent 
beyond the articular condyle. The inflected angle of the jaw, a, characteristic of the 
Marsupialia, is so abrupt in Thylacoleo that only the tip is visible in an outer view 
(fig. I, a), and this, with the angle, hardly rises above the level of the lower border of 
the ramus. In the Potoroo and Koala (ib., fig. 3) the angle (a) is relatively larger, 
rises higher, is less directly inflected, and the whole comes into the outer view of the 
ramus, as in other Marsupial Phytophagans (see fig. 4, Phalangista ; also the Paper of 
1871, p. 260, fig. 16, Dendrolagus, and fig. 18, Bettongia). 
In the vegetarian Diprotodonts the ascending ramus of the jaw supporting the 
articular condyle, c, and coronoid process, h, is relatively narrower and loftier than in 
the sarcophagous kinds. (Compare fig. 3 ( Phciscolarctos ) and fig. 4 ( Phalangista 
Cooliii ) with figs. 1 and 2, Plate 41.) The latter, indeed, comes nearer than Phasco- 
larctos, in retaining the small, seemingly, functionless denticles between p 4 and i 1 . 
But the crucial test is the shape and relative position of the articular condyle, c. 
In all existing Phytophagans it rises above the level of the molar series, in most 
considerably, as in the figures cited: in the existing carnivorous Marsupials, as 
Thylacinus (loc. cit., p. 235, fig. 11) and Dasyurus (ib. ib., fig. 12) it does not rise 
above that level. In the shape of the condyle, the transverse much exceeding the 
antero-posterior diameter of its convex articular surface, and in its sessile attachment 
forbidding predication of a neck, carnivorous characters are seen in Thylacoleo 
which are wanting in all Marsupial Phytophagans. In all the characters in 
which the mandible of the Marsupial Lion agrees with that of the smaller pouched 
Carnivores, the resemblance is still closer to that bone in the type Carnivores of the 
placental series. 
In the Paper of 1871 I was unable to oppose Professor Flower’s conjectural 
restoration of the mandible of Thylacoleo (loc. cit., p. 307), according to the type of 
that bone in the Koala and Potoroo by other than a conjectural restoration (ib. ib., fig. 8; 
and Plate 12, fig. 1) in which the inferred relative position of the mandibular condyle 
is indicated by the curved line, b, in the text. The two restorations may now be tested 
by the figures from nature in Plate 41. 
4 F 
mdccclxxxiii. 
