62 
THE VOYAGE OF H.M.S. CHALLENGER. 
above downwards, the apex of the wedge being anterior. The wedge was continuous by 
its base with the pedicle of its own side, and was marked laterally by the articular facet 
for the head of the 10th rib. The bodies of the 9th and 11th dorsals had a greater 
vertical diameter in front than is usual, so as partially to occupy the cleft between the 
separated parts of the body of the 10th, but the rest of the interval had doubtless been 
occupied in the recent spine by intervertebral disc. Owing to this defect in the body of 
the 10th dorsal vertebra it is probable that a slight posterior or angular curvature had 
been present during life in the lower dorsal region. 
There can of course be no doubt that in the 10th dorsal vertebra of this skeleton each 
of the two parts of its body had developed from a distinct lateral ossific nucleus instead 
of from a mesial nucleus, according to the normal arrangement ; and the lateral centres 
must have been separated by a considerable interval in the foetal spine, so as to allow 
of the relatively wide gap between the two wedge-shaped parts of the bone. It is 
possible that in the foetal cartilaginous spine the cartilage also may have been divided 
into two lateral parts not united mesially. This remarkable anomaly in the ossification 
of a vertebra is very rare, but the case is not unique. Rokitansky has described ^ the 
12th dorsal vertebra in a woman, age 55, as divided into two triangular rudiments, 
inserted laterally between the 11th dorsal and 1st lumbar vertebra, with their points 
directed inwards, and in consequence of the mesial defect in the body of this vertebra the 
column was bent backward at a very obtuse angle. Humphry saw in a specimen of spina 
bifida in the Berlin Museum ^ several of the vertebral bodies consisting of two halves with 
an opening between the two. Ahlfeld also refers ^ to a case observed by Ammon, in 
which the bodies of the 12th dorsal and 1st and 2nd lumbars consisted of two lateral 
halves. An approximation to this condition existed also in the vertebral columns 
described by Sandifort,* Otto,^ and Rokitansky,^ in which only one lateral half of a 
particular vertebra was developed ; in both Sandifort's and Otto's cases the half of the 
vertebral body which was present is described as wedge-shaped. 
The lumbar vertebrae had, as a rule, well-marked mammillary processes, but those on 
the 5th lumbar were not, for the most part, so large as on the four others. Accessory 
processes were usually present, but then- relative size varied in the difi"erent skeletons. 
In the Malay, a Hindoo, and a Lapp, they were strongest in the 1st lumbar ; in an 
Australian, Hindoo, Oahuan, and two Andaman Islanders, they were best marked in the 
3rd lumbar, in a Negro in the 4th lumbar. In some of the skeletons the four upper 
lumbars, in others only the three upper had them distinctly marked. The size of both 
the mammillary and accessory processes is, without doubt, correlated with the development 
of those deep muscles of the back which are attached to them. 
1 Pathological Anatomy, Syd. Soc. Trans., vol. iii. p. 232. ^ Human Skeleton, p. 124. 
3 Die Missbiltlnngen des Menschen, p. 296, 1882. * Musenm anatomicum, vol. iv. p. 74, Tab. clxxviii. fig. 2. 
^ Seltene Beobachtungen, zweite Sammlung, § 15. Op. cit., p. 231. 
* 
