SIR R. OWEN ON THE AFFINITIES OF THYLACOLEO CARNIFEX. 
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as many vertical grooves on the side of the crown terminate. Moreover, the so 
modified premolar is followed in the vegetarian Diprotodonts by four broad-crowned 
bruising teeth, instead of the suddenly reduced couple of conical molars (m, 1 and 2, 
figs. 1 and 2, Plate 1) by which Tliylacoleo resembles the placental Leonines. I view 
with interest the engrafting of a carnivorous modification upon a marsupial type of 
teeth and bone in a species equal as to size and force to grapple with and slay its 
ancient vegetarian contemporaries—the greater herbivorous Diprotodonts and Noto- 
theriums, the large, now extinct, Kangaroos, Sthenurus, Protemnodon, and the huge 
extinct Wombats ( Phascolonus )—types of pouched mammalian families, surpassing in 
bulk any of the allied still existing species. 
The picture of mammalian life in the Australian continent paralleled, of old, that 
still manifested in Asia and Africa : huge herbivorous quadrupeds were kept in check 
by large and powerful carnivorous ones, but both were represented by species of a 
lower grade of organisation; and the inferior cerebral development of the Marsupicdia 
may be taken into account when we attribute to the advent in Australia of the 
Bimanous race the extirpation of the beasts affording the greatest quantity of animal 
food, and the consequent reduction of the pouched families to such smaller existing 
species as are still able to escape by concealment in burrows, trees, and brush forests. 
Addendum. 
(Added 22nd December, 1886.) 
Since communicating the foregoing Paper, I have received from George Frederic 
Bennett, Esq., Corresponding Member of the London Zoological Society, a laige 
portion of a mandible of Tliylacoleo carnifex, discovered in the post-pliocene bed of 
King’s Creek, Toowoomba, Queensland, Australia; it is in the same semi-fossilised 
condition as the Diprotodont remains from that locality. 
The specimen may be seen, together with the cast of the entire mandibular ramus 
from the Wellington Valley Cave, New South Wales, in the Geological Department 
of the British Museum of Natural History, Cromwell Hoad. 
R. O. 
Description of the Plate. 
Fig. 1. Mandible of Tliylacoleo carnifex, nat. size, outside view. 
Fig. 2. Mandible of Tliylacoleo carnifex, nat. size, inside view. 
Fig. 3. Hind end of mandibular ramus of Tliylacoleo carnifex, nat. size. 
(References to parts in these figures are explained in the text.) 
B 2 
