The vertebral formula is C_{7}T_{13}L_{7(6)}S_{3}Cy_{20–23}.
The =cervical vertebræ= are relatively longer than in the ox and the
pig. The bodies of the typical vertebræ diminish in length from first to
last and are compressed dorso-ventrally. The anterior extremity is
moderately convex and the posterior slightly concave; both are oblique.
The median ridge and lateral grooves on the upper surface of the body
are very well marked. The second, third, and fourth have distinct
ventral spines. The spinous process of the third has the form of a long
low crest; in the remainder it is higher, blunt-pointed, and inclined
forward. The transverse processes of the third, fourth, and fifth
project downward and backward, and divide into two branches; of these,
the anterior one is thin, and the posterior is thick and tuberculate at
its free end. The process of the sixth has two parts; one of these is an
extensive quadrilateral plate directed downward and outward and ridged
on its inner surface; the other part is short and blunt, and is directed
outward and a little backward and upward. The seventh is readily
distinguished by its shortness, the length of its spine, and the single
transverse process. The posterior articular processes bear tubercles
which are large on the third, fourth, and fifth.
The ventral arch of the =atlas= is narrow from before backward, and
bears a small tubercle posteriorly. The upper surface of the dorsal arch
is strongly convex and rough centrally. The wings are wide, flattened,
and almost horizontal. The upper surface is rough. There is an alar
notch (Incisura alaris) on the anterior border instead of the anterior
foramen. The foramen transversarium is present.
The body of the =axis= is flattened dorso-ventrally, especially in
front. The odontoid process is rounded and relatively long, reaching
almost to the occipital bone; it is inclined upward a little. The
articular surfaces which flank it are condyloid in form and very
oblique. The inferior surface is wide, and is divided by a median crest
into two fossæ. The transverse processes are single, pointed, directed
backward and outward, and perforated by relatively large foramina
transversaria. The spinous process is thin and of moderate height, but
very long; it is prolonged forward so as to overhang the dorsal arch of
the atlas, and is terminated behind by a tuberosity which is connected
by two crests with the posterior articular processes. The anterior
notches are large and are never converted into foramina.
The bodies of the =thoracic vertebræ= are wide and compressed
dorso-ventrally, especially at each end of the region. Their convex
anterior surfaces are depressed in the middle. The posterior facets for
the heads of the ribs are absent on the last three or four. The
transverse processes resemble those of the horse. They bear mammillary
processes except at the anterior end of the region. The facets for the
tubercles of the ribs are large and concave in the anterior part of the
series, and become smaller and slightly convex further back. The last
three have accessory processes also. The first three or four spinous
processes are about equal in length. Behind this they become gradually
shorter to the tenth, and then remain equal. The backward slope is most
marked in the ninth and tenth. The eleventh is practically vertical
(anticlinal vertebra) and the last two incline slightly forward.
The bodies of the =lumbar vertebræ= are decidedly flattened
dorso-ventrally, and increase in width from first to last. The length
increases to the sixth. The transverse processes are plate-like and are
directed forward and downward. Their length increases to the fifth and
sixth. They form no joints with each other or with the sacrum. Their
extremities are enlarged, with the exception of the last. The accessory
processes project backward over the posterior notches of the first five.
The anterior articular processes are large, compressed laterally, and
bear mammillary processes. The spinous processes are broad below,
narrower above, and with the exception of the last, incline a little
forward. Their height diminishes behind the fourth.
[Illustration: