236 
PEOFESSOE OWEN ON THE FOSSIL M ANIMALS OF AUSTEALIA. 
It will be observed that, in the Thylacine — the most carnivorous of modern Marsu- 
pials — the depth of the notch between the condyle ( b ) and coronoid (c), or what Dr. Fal- 
coner indicates by the term “ pedunculate,” is relatively greater than in Sarcojphilus. 
The two recede in this respect progressively further from the Koala and the Aye-aye. 
If Plagiaulax had shown less degree of “ pedunculation ” and a higher position of the 
condyle than in Thylacinus or Sarcophilus, and had, in these respects, approached nearer 
to Cliiromys or Phascolarctos in mandibular modifications, an inference of corresponding 
approximation in diet, or herbivorous application of jaw, would have been legitimate. 
I claim the same quality for my conclusion, that as the carnivorous characters of the 
lower jaw are maximized in Plagiaulax (fig. 10) with strong indications of the same 
structure in Thylacoleo (fig. 8), so the carnivority of both genera is the more plainly 
demonstrated. 
It is not, however, a solitary character, but an association of characters, which esta- 
blishes this conclusion. 
Position of condyle relates to the force with which the mandible is worked, shape and 
pedunculation of the condyle to the direction of the working force. 
The flattened or less convex articular surface favours the rotatory movements ; the 
more convex, especially transversely extended and pedunculate or subpedunculate, condyle 
indicates the ginglymoid articulation with greater extent of divarication or wider gape, 
and more habitual movements of the jaw in one plane, or limited more or less thereto. 
The rotatory grinding movements of the mandible are commonly associated with a high 
position of the condyle and vegetable diet ; the vertical biting movements are commonly 
associated with a low position of the condyle and animal diet. But the advantage of a 
long lever afforded by a lofty coronoid process (figs. 10, 11, 12, c ) and low-placed condyle 
(ib. b) may correlate with powerful biting and gnawing actions, as in the working of the 
maximized scalpriform teeth of Cliiromys (fig. 9, i). 
Here, however, the coronoid ( c ) is comparatively low': the condyle (ib. b) is narrow ; 
its convex curve is chiefly longitudinal, or from above downward ; there is no constriction 
or neck ; the supporting part of the articular surface is continued directly upward and 
forward to the coronoid ( c ), and almost as directly downward and forward to the angle («)*. 
In similarly placed condyles for biting, piercing, lacerating, and killing actions of the 
mandible, and where such condyles are associated, as is the rule, with laniariform not 
with scalpriform anterior teeth, the condyle is more prominent ; the part of the ascending 
ramus supporting the condyle curves toward the coronoid process, in a course at first 
more or less deeply concave, then vertical or recurved ; and a similar well-marked con- 
cavity divides the condyle from the angle of the jaw, save in the most decidedly zoopha- 
gous of the Marsupialia [Sarcophilus, Thylacinus , Plagiaulax ), in the latter of which the 
convex condyle forms, as it were, the upper and back part of the angle itself. 
The condyle in Plagiaulax (fig. 10, b) projects a little below the horizontal level 
* Owen, ‘ Monograph on the Aye-aye,’ 4to, 1863, p. 20. pi. 8. figs. 7, 9 (also ‘ Transactions of the Zoological 
Society,’ vol, v. pt. 2. pi. 20. figs. 7, 9). 
