1862.] FALCONER PLAGIAULAX. 361 



sub vertical *. The glenoid surface of the upper jaw is modified in 

 correspondence — being broad and flat, and placed on an inclined 

 plane that would intersect the tips of the nasals and the middle of 

 the occipital foramen. Here, then, is a signal failure in the chain 

 of physiological deductions requisite to prove that Plagiaulax was a 

 marsupial carnivore. 



Next, as regards the depressed position of the condyle — below the 

 level of the grinding-teeth. The author of ^ Palaeontology ' states 

 that it is a '' character unknown among any herbivorous or mixed- 

 feeding animal." I again refer my reader to the figure (fig. 20) of 

 the lower jaw of the Aye- Aye. In it, the articular surface of the 

 condyle, although directed subvertically, or at the most diagonally, is 

 wholly below the grinding-plane of the molars. It looks still more 

 depressed in Plagiaulax BecJclesii ; but this is, in part, owing to the 

 inflected margin of the angle being broken off in the fossil, while it 

 is entire and salient in the recent form, thus elevating the condyle 

 above the lower plane of the ramus, and leading to an appearance of 

 a greater amount of difference than exists in nature t^ 



For my reasoning as regards the signification of the long neck or 

 pedicle of the condyle, I refer the reader to my former communication 

 (ojQ. cit. pp. 269 and 275). It is there stated that the low position of 

 the condyle '' 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," 

 &c. ; and further on I added that the " arrangement is equally without 

 a parallel among the herbivorous or omnivorous tribes." This latter 

 remark was premature. I was then acquainted with the Aye-Aye 

 only through the figures given by Blainville +, in which the lower 

 jaw is shown in opposition with the skull, thus concealing the coro- 

 noid, and its relation to the condyle. But if the accompanying figure 

 (fig. 20) of the lower jaw detached be referred to, it will be seen that 

 the condyle is not only below the level of the grinding-plane, but 

 that it is projected a long way behind the posterior edge of the coro- 

 noid, exactly as in Plagiaulax, and on the same plan of construction, 

 — the sole difference being that the sigmoid notch is shallow in the 

 Aye- Aye, and deeply excavated in Plagiaulax. If the notch were 

 deepened in the former, by removing the plate of bone behind and 

 below the posterior edge of the coronoid, in the manner indicated by 

 the dotted line (/), the resemblance would be complete. In order 

 to place these facts of agreement beyond question, I give the following 



■* " La machoire inferieure, comme celle des autres rongeurs, se meut evidem- 

 ment au moyen d'un condyle longitudinal, de maniere a empecher tout mouve- 

 ment horizontal, si ce n'est de I'arriere a I'avant et vice versd.''^ (Sandwith, Zoo- 

 logical Proceedings, 1859, p. 113.) 



t In some of the families of the JRodentia the condyle is barely elevated above 

 the grinding-plane of the molars. See Blainville ' Osteographie : genus Cavia^ 

 pl. 2. Figs. Cavia Cohaya and C. Capybara ; genus Hystrix, pi. 2, and Sciurus 

 raax'imus, pl. 1, while in others, e. g. Castor, both condyle and coronoid are well 

 raised above the same plane. 



I Osteographie : genus Lemur, pl. 5. 



