72 THE KEILOR FOSSIL SKULL: PALATE AND UPPER DENTAL ARCH 
Flower’s method (5) of determining the degree of prognathism 
is used for estimating the Gnathic Index. The length of the Basion- 
Alveolar Point chord is multiplied by 100 and divided by the 
length of the Basion-Nasion chord. 
Gnathice Index oo 
Reilor-skwl ..c) wee Vs SPOR 
Tasmanian adults .. .. .. 101°4 (93°3-107 6) 
Australian adults .. .. .. 1045 (93:'1-115°3) 
The condition is thus expressed : 
Orthognathous—when the index is below 98. 
Mesognathous—when the index is between 98:1 and 103. 
Prognathous—when the index is above 103. 
The Keilor skull and average Tasmanians are therefore mesog- 
nathous and average Australians are prognathous. 
The palate is large and the upper dental arch is horseshoe- 
shaped, with the third molars and post-dental processes curving 
well inwards (Pl. X, fig. 1). It is not quite symmetrical, the right 
side being slightly larger than the left. The sagittal suture is 
plainly visible, but the transverse and pre+maxillary sutures are 
obscure, possibly on account of incomplete removal of the cal- 
careous incrustation which originally covered the whole palate. 
There is a narrow, low maxillary torus which is slightly higher on 
the left than on the right side ; it is continuous with a large palatine 
torus. The palate is very broad in relation to its length. 
An interesting feature is an unerupted tooth lying in the sagittal 
plane in the maxillary torus on the left side ; it is probably a super- 
numerary tooth, since all teeth of the permanent dentition or their 
sockets are present. Most of the tooth is covered with bone and its 
form cannot be determined. Professor A. Amies of the Melbourne 
University radiographed the palate from various angles, but the 
anaes incrustation in the nasal fossae prevented satisfactory 
results. 
The following are measurements of the palate: the first three 
are those used by the Galton Laboratory and the remainder are 
Campbell’s: 
G’1. Palate length; from orale to staphylion, 56°5 mm. 
Go. Palate breadth; distance between points on the alveolar border on 
the palatal side of the upper second molar teeth, 47-2 mm. 
EH. Palate depth from Gy, chord to the median palatal suture, 13-5 mm. 
p-p- Inner palatal width on the alveolar border opposite the second 
premolars, 41 mm. 
CC Inner palate width opposite the cuspids, 33-5 mm. 
