RECORDS OF W.A. MUSEUM. 
[57 
The specimens identified as belonging to Thylacoleo are not 
numerous, they include however, the large upper and lower incisors, 
the third upper incisor, formerly regarded by Prof. Owen as the 
canine, the characteristic upper and lower PM4 and a fragment of 
the maxilla and malar bearing in situ a perfect left upper premolar 
(PM4) with the adjacant first molar, both these teeth are very 
much worn and evidently belong to a fully developed animal. 
In addition to these there is a small fragment of the left lower 
jaw with sockets of the last molar and a portion of the anterior 
border of the coronoid. 
These teeth and fragments, in showing signs of much wear, 
all suggest that the aged animal (or animals) to which they belonged 
was from i-4th to i-5th smaller than the animals described and 
figured by Prof. Owen and Prof. McCoy. 
The first upper incisors, plate vii., figs, i and 2, are mostly 
fragmentary ; they show that the perfect tooth is curved and 
compressed, and the enamelled area practically confined to the 
anterior and exterior surfaces, as in the wombat and the Rodentia. 
The greatest vertical extent is at the antero-exterior angle of the 
tooth. On the inner side there is a wedged shaped border confined 
to the anterior margin, and with its base at the cutting edge. On 
the posterior aspect the condition was originally similar, but 
continuous wear has removed much of the enamel which is now 
almost entirely confined to the cutting edge, a groove in the dentine, 
presumably caused by the friction of the lower incisor is most 
distinct. 
The distribution of the enamel is entirely different on the 
canine teeth of the Carnivora, which are completely covered on 
their exposed surfaces and therefore much more powerful than these 
incisors. 
The third upper inciSor in the collection closely resembles the 
tooth figured by Prof. Owen in Phil. Trans., 1871, Plate xi., fig. ii, 
which Krefft states is the third incisor but which according to 
plate xn., figs. 15-18, accompanying his article, should be one of 
the premolars This latter designation is evidently an error, for 
1 Krefft. Ann. and Mag. Nat. Hist., Series 4. Vol. X., 1872, p. 172. 
2 Log. cit., p. 182. 
