78 
THE VOYAGE OF H.M.S. CHALLENGER. 
STERNUM. 
The sternum was present in thirty of the skeletons. As a rule the prse- meso- and 
xiphi-sternal segments were not united to each other, and the xiphi-sternum had usually 
been lost. In the following specimens this rule was departed from. In the Perth 
Australian and the Sikh, the prse- was fused with the meso-sternum, but the xiphi- 
sternum was free. In an Andaman Islander and the Malay the xiphi-sternum was 
ossified and fused with the meso-sternum, but the manubrium was free. In an Andaman 
Islander, in which the epiphyses of the long bones were not fully ossified to the shafts, 
the prse-sternum was fused with the first segment of the meso-sternum, but the latter was 
not ankylosed to the second segment, and in the lowest segment of this division of the 
bone the two lateral halves were imperfectly united mesially. In the Chinese the first 
segment of the meso-sternum was free, but the second, third, and fourth segments were 
fused together, and the xiphoid was ossified but not fused with the meso-sternum ; this 
skeleton, from the ossification of the long bones, apparently belonged to a man from 
twenty to twenty-four years of age. In the Manly Cove Australian, although all the 
segments of the mesosternum were ankylosed together, yet a distinct fissure marked the 
plane of fusion of the first and second segments. 
In the Bush skeleton, the Malay and the male Lapp, the meso-sternum was perforated 
by a hole, large enough to admit a quill, situated at the junction of its third and fourth 
segments ; in the Malay the first pair of costal cartilages were ossified on the surface. 
A meso-sternal hole due to defect in the ossification of the cartilaginous sternum is 
sometimes seen in Europeans. 
These sterna do not throw much light on the question whether the manubrium or the 
xiphi-sternum unites first with the meso-sternum, for whilst there are two cases of fusion 
of the xiphi-sternum, without ankylosis of the manubrium, there are also two cases of 
fusion of the manubrium without ankylosis of the xiphi-sternum. There is also one 
remarkable instance of fusion of the manubrium with the first segment of the meso-sternum 
before the meso-sternum itself had completed its ossification, but this is quite exceptional. 
It is without doubt the rule for the manubrium not to fuse with the meso-sternum until 
comparatively late in life. The Malay skeleton and one of the Oahuafc women show that 
ossification of the costal cartilages may have considerably advanced without the prse- and 
meso-sternum having become ankylosed together. The condition of ossification of the 
sternum does not, I think, afford any accurate guide to the age of the skeleton, and in 
this respect my observations conform with those of Dr. Thomas Dwight . 1 
1 The Sternum as an index of Sex and Age, Journ. Anat. and Phys., vol. xv. p. 327, 1881. 
