BY C. VV. DE VIS. 
103 
Lower premolar elongate, bicuspidate, without intero-posterior 
cusp. Molars smooth or with accessory plates, without posterior- 
groove or basal talon. Lower contour line of mandible a gentle 
curve throughout. 
Dimensions. 
Mandibular. — The full series of true molars is 39*0 in length 
when aged 1); the first four cheek-teeth measure 38*0 (1); the 
first three 28-6 (1); the last three 30-5 (1); the last two 22-5 and 
23-5 (2). The premolar 7'5 and 8'0 (2). The width of m. 3 is 
from 7'7 to 8-4 (6). The anterior depth is from 20-2 to 23-5 (4); 
the posterior from 18-4 to 22-0 (5); the thickness from 10*1 (aged) 
to 14-1 (5). The external length is 92-0; the internal 72-0. 
Though the thickness of the mandible has the same range as in 
H. agilis, which of modern wallabies has the stoutest underjaw, 
its length and depth are comparable with those of the kangaroos 
only. This is also the case with the length of the cheek-teeth, 
which may be estimated at 50*0 in young adults, and with the 
width of the molars, but from the kangaroos it is at once 
distinguished by the structure both of premolar and molars. 
Form. 
Mandibular. — P. 4 (PI. xvn. fig. 1) elongate, narrow, diameters 
8-0 x 3 4, bicuspid; crest a little to the inner side, deeply notched 
at its anterior two-fifths. Anterior cusp a well defined strongly 
compressed cone separated from the longer posterior part of the 
lobe by a deep gooove descending upon each side of the crown 
nearly to the base and by the notch in the crest; a slight incras- 
sation of the crown over the intero-posterior angle does not affect 
the general parallelism of the sides. Equal in length to m. 1 . 
Molars. — (PI. xvii. fig. 2). These show a tendency to develop a 
single erect compressed process at the bottom of the inner mid 
valley — i.e., a rudiment of an accessory link similar to that in the 
upper teeth of Palorchestes and M. "pan (infra ). This process 
occurs in two examples. 
