V e r t e b r a l C o l u m n .
O f this part o f the skeleton o f the Scelidothere, Mr. Darwin’s specimen includes
as IS represented in P la te X X ., the cei-vical. part o f the dorsal, and the sacral series
ot vertebræ m a more or le ss perfect condition.
The cervical vertebræ present the ordinary mammalian number, seven and are
free, or so articulated as to have permitted reciprocai movement upon each
other. Tlieir transverse processes are perforated as usual for the vertebral
Z T Z ‘1'^ «‘1“ " e remarkable for their great breadth,
ength, and thickness ; and indicate the muscular forces which must have worked
the head upon the spine to have been very powerful. The a x is is provided with a
robust ‘ processus dentatus.’ having a base equal in breadth to the body o f the
axis itself ; and a smooth articular convexity on the side o f the apex on whicli the
ring of the atlas rotated. The line o f union between the axis and its characteristic
process, w inch here resembles the body o f an abortive vertebra, is very distinct The
transverse processes o f the vertebra dentata are comparatively feeble, but this con-
compensated for by the great development o f the spinous process.
f i . X X I V. fig. 1.) Th is process is bent backwards at nearly a right angle ovei-
hips with Its reflected extremity the spine o f the third cervical vertebra, and rests
by Its base, on the under part o f which are the posterior articular surfaces, upon
the broad and strong anterior oblique processes o f the third vertebra.
The third, fourtli, fifth, and sixtfi cervical vertebræ have moderately developed
and pointed spiiions processes: their transverse processes are broad, and ext™d
obliquely backwards, and sligh tly overlap each otiier. On the under part o f the
transver.se process o f the sixth cervical vertebra tliere is the fractured base o f what
conjecture to have been an expanded aliform plate, analogous to that observable
m the corresponding vertebra o f the Orycterope. The seventh cervical vertebra
has part o f the articular depression for the l.ead o f the first rib upon each side o f
hei!ht^„ ' Z developed, but tlie spine is double the
height and size o f those o f the preceding vertebræ
height o f the preceding spine o f the seventh cervical, and preserves an equal antero-
p erior diameter from its base to its summit, which is thick and slightly bent
backwards : four or five succeeding dorsal vertebræ give evidence o f having been
surmounted by spines of equal height and strength. The transverse processes o f
t in o f r t'^ r i'"* °» ‘heir inferior part for the reception
o f the tubercles o f the ribs, and they gradualiy ascend upon the base o f the
-pines as the vertebræ are placed further hack, so as to increase the expansiveness