302 The Spinal Curvature in an Aboriginal Australian. [Jan. 24, 



in the Chimpanzee the lumbar curve passes continuously into the 

 sacral region, and involves one, or perhaps two, of its vertebrae. 



In connexion with this question, it is interesting to note the close 

 association which the last lumbar vertebra in the Chimpanzee 

 exhibits with the sacrum. The intervening disk of cartilage is very 

 thin, and quite different from those above it. Further, it is extremely 

 common to find the last lumbar vertebra of the Chimpanzee pre- 

 senting sacral characters and joined by osseous union to the sacrum. 

 In the Australian and European the last lumbar and first sacral 

 vertebrae are well separated from each other by a thick pad of inter- 

 vertebral substance, but there is reason to believe that the last 

 lumbar vertebra of the Australian more frequently exhibits sacral 

 characters than the corresponding vertebra of the European. 



6. A single glance at the tracing obtained from, the mesial section 

 of the Australian spine will be sufficient to dissipate any doubt that 

 may be remaining regarding the presence of a lumbar convexity in 

 the vertebral column of this race. Not only does it exist, but it 

 exists in a very pronounced form. The degree of curvature in the 

 lumbar region of the Australian, while it falls slightly short of that 

 which is seen in the Chimpanzee, corresponds closely with the 

 degree of curvature in the European female. At the same time we 

 must not lose sight of the fact that the lumbar curve does not 

 consolidate until adult life, and the Australian spine was taken from 

 a girl who had only reached the age of sixteen. It is more than 

 probable, therefore, that the spine in question does not express the 

 full amount of curvature of the lumbar region in this race. 



7. In the Australian, the curvature in the lumbar region is entirely 

 due to the strongly wedge-shaped form of the intervertebral disks. If 

 we lorm an index for these, as has been done for the vertebral bodies, 

 the amount which they contribute to the curve can be appreciated. 

 The following are the indices obtained for the Australian spine, and 

 also the average indices of the spines of four Europeans : 



Lumbo-vertebral Lumbo-intervertebral 

 index. index. 



Australian 101'6 49'5 



Four Europeans 96'3 65*6 



8. In the extended paper the character of the lumbar axial curve is 

 discussed, and it is shown to differ materially from that of the 

 European. In both it is composed of the arcs of three circles. The 

 parts entering into these, and the lengths of their respective radii 

 differ in the two cases markedly. In the Australian the lower part of 

 the curve is abrupt and sudden ; in the European it is more uniform 

 throughout. 



9. A sagitto-vertical index of the lumbar vertebras suggests some 



