Prof. Owen on an Incisor of Nototherium Mitchellii. 475 
LXI.—On an Upper Incisor of Nototherium Mitchellii. 
By Professor R. Owen, F.R.S. 
[Plate XVI.] 
To the Editors of the Annals and Magazine of Natural History. 
GENTLEMEN, 
I have received, through the kindness of Sir Daniel Cooper, 
Bart., from the freshwater beds of Gowrie Creek, Darling Downs, 
Queensland, an upper front incisor, right side, of the Nototherium 
Mitchell (P1. XVI.), which so closely accords in size with the 
dimensions of the tooth described and figured in the December 
Number of your volume xvi. (1865) p. 448, by Prof. M‘Coy, 
that I am disposed to ascribe that tooth also to the species near 
the remains of which it was found, “at Murchill, not far from 
Geelong, Victoria.” 
My specimen is 5 inches 1 line long in a straight line, 
1 inch 73 lines in the greatest (fore-and-aft) diameter, which is 
about the middle of the root; 10 lines in greatest transverse 
diameter. The enamelled crown, e, is 1 inch in length, be- 
velled off, chiselwise, from before downward and backward, 
and shows the partial application of enamel usual in such 
teeth ; the free margin on the outer side of the crown (fig. 4) 
extends further back than that on the inner side (fig. 1 e), 
and is slightly everted: it is also thicker than the even 
inner border. The breadth of the unenamelled back part of 
the crown (figs. 1, 3, 4d) at its base is 64 lines: owing to the 
difference in extent of enamel on the sides of the crown, the 
abraded surface slopes from without imward and backward, as 
well as from above downward and backward. The enamel is 
1 of a line in thickness at the outer side of the crown: the 
whole outer surface is smooth. The crown is broadly convex 
anteriorly, rather flatter on the inner than on the outer side. 
The root is more thickly covered by cement, and increases in 
every dimension, chiefly from before backwards, as it recedes 
from the crown, until at a little below its midlength it attains 
the dimensions above given: it then diminishes to the pulp 
end. The outer side begins to be impressed by a longitudinal 
shallow channel about an inch and a half below the crown; 
and this channel increases in breadth, but not in depth, be- 
coming, indeed, shallower near the pulp end of the root. On 
the inner side, the longitudinal channel begins somewhat 
nearer the crown, and sinks deeper as it recedes, besides 
becoming wider. The tooth is “compressed and gently in- 
curved,” or, rather, “recurved,” the front margin describing 
a greater convexity, lengthwise, than the hind margin: the root 
