376 Transactions of the Boyal Society of South Africa. 
Sacrum. 
The measurements and indices utilized in the study of the sacrum are 
as follows : — 
1. Sacral Index = 
Breadth of base of sacrum x 100. 
Length from middle of promontory to middle of anterior-inferior 
border of fifth sacral vertebra. 
The length is measured with callipers, but Cunningham (Glasgow, 
1900) pointed out that this could not be regarded as the true length, for it 
did not take into account the curve of the sacrum, often a very consider- 
able factor and showing racial character. He therefore suggested that 
the length should be measured from the points mentioned above along the 
concavity with a steel tape held in position by a flexible strip of lead. I 
append a table from Professor Cunningham's Lectures to his class of 
Anthropology in Edinburgh University, of which I was a member, show- 
ing the differences between the indices constructed from the callipers and 
tape measurements, and how the index largely depends on the condition 
of the curve. 
Calliper Index. 
Tape Index. 
Curve Index. 
Irish Female, A . . 
125-7 
108 
19-4 
Irish Female, B . . 
158-3 
110 
32 
Irish Male, A 
110 
96-6 
22-5 
Irish Male, B 
126-7 
98-4 
28 
Torres Straits Male 
108 
100 
17-5 
Torres Straits Female 
115 
101-8 
19-5 
Andaman Male 
118 7 
106-3 
17-8 
Negro 
103-5 
97-5 
11-5 
Australian . . 
89 
86-6 
11-6 
Chimpanzee 
82-5 
80-6 
5-6 
2. Sacral Curve Index = 
Depth of curve from deepest part of curve to line joining middle of pro- 
montory to middle of anterior inferior border of fifth vertebra x 100. 
The length of curve measured by flexible tape. 
Sacral Index. 
S.A.C. 1. 
S.A.C. 2 
S.A.C. 3. 
Female. 
Male. 
Male. 
Sacral Length, Callipers. . 
99 
93 
103 
Sacral Length, Tape 
106 
98 
105 
Sacral Breadth 
99 
94 
92 
Callipers Index 
100 
101 
89-3 
Tape Index 
93-4 
95-9 
87-6 
