424 PLAGIAULAX. 



molars to a herbivorous regimen. The wear of the two true 

 molars would seem to indicate a grinding, as contradis- 

 tinguished from a crushing or cutting action of the teeth; 

 and this is confirmed by the form of the articulating surface 

 of the condyle. 



The characters of the jaw are so peculiar, and in some 

 respects of so mixed and complex a nature, that they require 

 to be weighed with caution, in conjunction with the teeth, in 

 forming any opinion regarding the affinities of Plagiaulax. 

 The low position of the condyle is so pronounced, and the 

 elevation of the coronoid above it so considerable, that re- 

 garded per se, supposing no teeth had been discovered, they 

 might have been considered to imply with some degree of 

 certainty, a predaceous animal. The condyle is even re- 

 latively lower in Plag. Becklesii than in Thylacinus, Dasyurus, 

 and Diclelphys, the most carnivorous among marsupial forms. 

 A condyle so placed was considered by Cuvier to be a positive 

 indicator of the ferine type. But in Plag. Becklesii, the force 

 of the indication is counterbalanced by another character, of 

 which, so far as I am aware, there is no example among any 

 of the predaceous genera, either placental or marsupial, recent 

 or fossil, namely, the long neck and horizontal projection of 

 the condyle behind the coronoid, the term ' neck ' being used 

 for convenience to imply the constricted portion of the ramus 

 between the bottom of the sigmoid notch and the lower 

 margin. In all the ferine animals the pivot of motion or 

 transverse condyle is, for obvious mechanical reasons con- 

 nected with the functions of the jaw, brought on a short stem 

 close under the base of the coronoid process. In Plagiaulax 

 it is carried out upon a long pedicle behind, and, pro tanto, 

 there is a great deviation from the predaceous type. The 

 arrangement is equally without a parallel among the herbi- 

 vorous or omnivorous types, in which the condyle is ordi- 

 narily elevated above the horizontal plane of the teeth, with, 

 more or less freedom of lateral or longitudinal motion. Fur- 

 ther, the convex articular surface of the condyle, and its 

 vertical instead of transverse direction, are at variance with 

 the locked implantation of the jaw of a ferine animal. The 

 other leading indications all lean towards a vegetable feeder, 

 namely, the limited surface and moderate elevation of the 

 coronoid above the plane of the teeth ; the feeble develop- 

 ment of the inflected margin, and the absence of a thick 

 angular process ; the advanced position of the orifice of the 

 dentary canal ; the offset of the inflected margin above it, 

 and the form of the symphysial suture. These characters, 

 taken in conjunction with the marked signification of the 

 teeth, would seem clearly to place Plag. Becklesii among the 



