188 
MASARU NAGAO 
latter can be inferred from the length of the radius of the curve, as 
may be seen from the tables. To illustrate the points just mentioned, 
the data in tables 21 and 22 were arranged according to the dimin- 
ishing value of the dental index in orang utan and in the primates. 
TABLES 23 AND 24 
Data Pertaining to the Gnathic Index, and the Length or the Radius of the 
Curve of Spee. Arranged According to the Diminishing Values 
for the Gnathic Index 
TABLE 23 
Primates 
WAIIE OP SPECIES 
GNATHIC INDEX 
RADIUS 
degrees 
Cfft. 
151 
7 A3 
143 
10.17 
135 
6.02 
122 
7.82 
120 
5.50 
Semnopithecus femoralis 
106 
5.94 
Man 
101 
7.55 
TABLE 24 
Simia satyrtis (orang utan) 
Simia satyrus (orang utan) : 
1563* 
163 
8.38 
2223 
159 
9.46 
5646 
15S 
8.03 
7064 
151 
5.51 
2170 
148 
6.58 
2172 
143 
6.68 
2222 
140 
7.35 
*Nxunber of the skull of Simia satyrus. 
Spee states in his paper (1890) that, in general, the greater the 
radius of the cyHnder-surface on which the occlusal line of the teeth 
lies, the bigger will be that animal, and the more prognathic the skull. 
"Der Radius des Cyhnder-mantel, auf dem sie liegen, ist im AUge- 
meinen um so langer, je grosser das Tier, je prognater der Schadel 
ist." As will be seen from the tables, the results of my measurements 
show no correlation between the length of the radius, which measures 
