Principle in Palaeontology. 175 



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." This is not quite correct, 

 the condyle of the herbivorous phalanger known as Dactylo- 

 psila trivirgata being lower than the row of grinding teeth. 



On April 19, 1870, I wrote to Professor Owen, saying,, 

 " The carnivorous character of our friend Thylacoleo is greater 

 than I first thought it was. I firmly believe the cast of a con- 

 dyle I sent you is that of this animal." These remarks were 

 made when I had noticed the row of teeth to be in a line with 

 the ascending ramus, which is a more or less carnivorous cha- 

 racter in marsupials. 



June 13, 1871 (evidently too late for the paper under dis- 

 cussion), I wrote again : — "Regarding the Thylacoleo I wish to 

 assist you as much as possible to arrive at a correct determi- 

 nation of the animal's character. I sent you already what I 

 consider the condyle and angular process, in fact the very part 

 which is missing. If you choose to believe me, it is the iden- 

 tical left posterior portion of the jaw, whereof we possess the 

 right anterior one also. The jaw is very much like that of a 

 koala ; and the condyle resembles it more than that of any 

 other animal." With this letter I despatched a series of careful 

 tracings of my sketches, including one of an upper canine of a 

 tiger and the lower incisor of a Thylacoleo^ for comparison. 



Nearly a year has passed since this letter was written ; and 

 my opinion that the animal under discussion is a mixed feeder, 

 allied to the phalanger tribe, is more and more confirmed. 

 There is no occasion for me to fall back upon the Purbeck 

 fossils, or to ransack all the countries under the sun for allied 

 forms ; I have only to examine the numerous recent skulls of 

 our marsupials collected for a purpose like the present during 

 the last twelve years, and I am able to form a very good idea 

 of the " leonine marsupial." 



I believe, and am ready to prove presently, that the Thyla- 

 coleo contained in its structure certain characteristic parts from 

 each of our principal marsupial groups. Let me describe the 

 upper jaw : — The first pair of curved incisors (PL XL fig. 2, 

 and PI. XXL fig. l,a) resemble those of the Belidanisjlaviventer 

 or "yellow-bellied tlying phalanger." The next pair {b), as 

 Avell as the third (c), are as near in shape to those of the 

 " bettong " as can possibly be imagined. The canine [d), with 

 its compressed crown, is also " bettong-like," and differs con- 

 siderably from that of the phalangers proper. The disposition 

 of the incisor teeth is the same as in the " bettong " (PI. XL 

 fig. 8), the curved first incisor arching above the close-packed 



