110 
FOSSIL JAWS OF MACROPOD1D.E, 
vary from 28*3 to 29-1 (3); the first two are 19-5 (1); the pre- 
molar measures from 10*0 to 13*0 (8). The true molar series 
ranges from 40-0 to 48-1 (8); the last three from 34-3 to 41 -1 (9); 
the last two from 23-8 to 28-6 (12);' the first three from 29-4 to 
38-1 (5); the first two from 20-5 to 22-6 (4); m. 2 , m. 3 are 27-1 
(1); m. 3 13-0 (1); m. 4 is from 13-2 to 14-4(7). The width of 
m. 3 is from 8*0 to 10*5 (37). The anterior depth of the mandible 
varies from 22-0 to 30-0 (20); the posterior from 19-4 to 29-9 (21); 
the thickness from 12-7 to 18-8 (31). 
It will be apparent from these measurements that though their 
maxima overlap in some cases the minima of H. anak the 
differences between their minima and the maxima of the other 
are far too great to be ascribed to the elasticity of a single species 
even were all the teeth indistinguishable. The existence of a 
dwarfed variety of H. anak conterminous and contemporaneous 
with it is too unlikely to be worth considering. 
The probability that upper and lower jaws are in this case 
rightly associated rests on the grounds of corresponding size and 
premolar structure. 
Form. 
Mandibular. — The premolar p. 4 (PI. xvn. fig. 12) as extracted 
from its chamber in an advanced stage of growth is an elongate- 
ovate symmetrical tooth with a cuneiform crown and diameters 
10*7 : 4-4. The crown is compressed as to its mesial two-thirds, 
more deeply on the inner side. Three mesial ribs on each side 
form serrations on the crest which is central. There is no 
dilatation or tumidity of the intero-posterior angle, but the end of 
the crest inclines slightly inwards. In the worn state these teeth 
can be distinguished from old teeth of H. anak only by their size. 
The deciduous premolar p. 3 (PI. xvn. fig. 11) is very similar to 
that of H. anak, convex on the outer, nearly straight on the inner 
side, with a slightly developed intero-posterior cusp which renders 
the inner side somewhat concave posteriorly. Diameters 7*0 x 
3-9. 
Maxillary. — The premolar p. 4 (PL xvn. fig. 13) is elongate- 
triangular, with diameters 13 x 7*8 (basal). Crest central 
