RECORDS OF W.A. MUSEUM. 
[65 
incisor which has lost the tip of its root is very much worn, more 
than half the enamel on the inner side having been removed. The 
ower portion of the enamelled surface on this face is worn and 
polished by the friction of the other incisor, showing that the 
symphysis was lax and that, by a motion of the jaws, the two 
incisors worked against one another in a scissor-like manner. 
The jaw differs from S. occidentalis in its general outline, the 
contour of its inner and outer surfaces, the greater extent of the 
cheek teeth (P4 M4), which is 70mm. against 62mm. in the other 
species, and by the greater dimensions, both longitudinal and trans- 
verse, of all th« individual teeth. On the other hand, this 
Balladonia animal has many points in common with the one whose 
broken mandible is figured by Owen (loc. cit., plate xxn., fig. 9, 
and plate xxiv, figs. 7 and 8). The extent of the tooth series and 
of P4-M2, the contour of the bone and the dimensions of the 
individual teeth are identical. 
The length of the tooth series and the measurements of the 
mandible do not come within the limits given by De Vis 1 * in his 
description of the species, but, as the specimen figured by Owen 
has not been excluded by this authority when he restricted the 
species, and has been allowed to stand by Lydekker 5 in his 
catalogue, this jaw may be regarded as a true 5 . atlas. 
A third specimen, consisting of the greater part of the 
horizontal jaw with roots of the four molars, may be included ; it 
has an outline similar to the preceding, but has its lower margin 
perfect. 
This animal is new to the State. Its home has, up to the 
present, been considered to be in Queensland and New South 
Wales. The finds at Balladonia have greatly extended its range. 
1 Proc. Linn. Soc , N. S. Wales, 2nd Series, Vol. X., p. 98, 1895. 
a Loc. cit., p. 233. 
