124 
malia, Part V. (Lydekker, 1887), p. 157, Sceparnodon appears 
as a synonym of the definitely established genus Phascolonus ; so 
also a similar view has been adopted in Mammals Living and 
Extinct (Flower and Lydekker) p. 146. 
Elsewhere* Lydekker has stated the reasons on which he 
bases his conclusions as to the generic identity of the two forms. 
On the other hand their identity has been disputed by DeVis,7 
who, in the latter of the two communications referred to, 
describes and figures, as the real incisor of Phascolonus, a tooth 
of a form very different to that ascribed by Owen to Sceparnodon ; 
but whatever this tooth may be, it is certainly not that of Owen’s 
Phascolonus. 
In the light of DeVis’ statements, Lydekker expresses himself 
more doubtfully on the subject in his later work, ‘“‘ Marsupials 
and Monotremes,” 1894, p. 266. 
The very complete evidence afforded by the Callabonna re- 
mains will, now however, finally decide the point in favour of 
identity. { 
As regards the first proposition the assertion rests on the clear 
evidence afforded by the Callabonna discovery.§ Amongst these 
remains, and associated with others of the same animal, were two 
mandibles, nearly complete except as to the upper two-thirds of the 
ascending ramus, which corresponded exactly to those of Owen’s 
Phascoiomys (Phascolonus) gigas. One of these mandibles 
belongs to other fragments which, together, make up a large por- 
tion of the cranium. Fortunately the maxillary portion is included 
and in this are implanted a nearly perfect pair of the adze-like 
teeth in question, these having precisely the same characters as, 
though they are rather larger than, those ascribed to Sceparnodon 
by Owen. Of this pair the left allows its length to be taken 
from the chisel edge for a length of 160 mm. along its convexity 
to its broken implanted end. The right tooth has lost one inch 
of its anterior extremity but has preserved about that amount 
more of the implanted end than its fellow. Thus we may be sure 
that the whole length of the perfect tooth must have been at 
least 180 mm. but it was probably not much more, as ‘the 
considerable amount of pulp cavity exposed at the broken 
implanted end of the right tooth indicates that its posterior limits 
had been nearly reached. This limit corresponds to a vertical 
drawn through the upper premolar. The width of these teeth 
* Proc. R. Soc. vol. XLIX., 1891, p. 60. 
+ Froc. Linn. Soc. of N.S.W., 1891, vol. VI. (2), pt. 2, p. 258, and vol. 
Wai, 1893 (2); pies p.- 11: 
{Fora review of various opinions that have been expressed on this 
question vide an article by Dun in the Records Geol. Survey of New South 
Wales, vol. III., 1892, p. 25. 
§ Nature, vol. L., 1894, pp. 184 and 206. 
200 So te Aa eee re ia 
