flattened, than in Inia, and it is marked by a pointed longitudinal ridge or spine,
and it is rather deeply notched anteriorly at its base, for the suboccipital nerve and
vertebral artery; and above the facet for the occipital condyle, a sharp process projects
upwards and inwards from the inferior to the superior angle of the notch to
such an extent that it is possible the notch in some individuals may become converted
into a foramen. The inferior arch is very broad and strong, having a well-
developed hypapophysial process for the support of the odontoid and a large concave
facet on its upper surface for its reception. The posterior zygapophyses are unsym-
metrical, the left being considerably larger than the right, and projecting inward
beyond the inner wall of the neural canal, which it also renders unsymmetricai.
The base of the left facet and the right half of the odontoid facet are slightly raised
above the level of the corresponding parts on the left side. The upper surface of
the posterior facets are deeply grooved. The neural canal is broad above and narrow
below.
The axis is distinguished by its very largely developed superior transverse process
directed backwards and outwards. The odontoid is well developed and has a
large, articular facet on its under surface, and it is slightly twisted to the left.
The neural canal is broader than high and arched with a broad flattened floor. The
arch is broad, antero-posteriorly high, directed slightly backwards, and the spinous
process is traversed by a well-marked ridge which terminates anteriorly in a free
process, the apex of the spinous process being more or less bifid. The body of the
axis is concave below and terminates in two posteriorly divergent, strong hypapo-
physes. The anterior zygapophyses, the upper extremities of which are on a level
with the inferior border of the posterior zygapophyses, their inferior margins being
on a line with the under surface of the odontoid, partake of the same want of
symmetry that distinguishes the posterior surfaces of the atlas. Their surfaces are
not continuous with the articular surface of the odontoid, so that the lateral
movement of the head cannot be very great. The articular surface of the
centrum is transversely oval, and the epiphysial surface markedly concave in the
middle.
The third cervical has a very short centrum, a little broader than high. The
neural canal is triangular, considerably broader than high, and with very narrow
laminse, directed slightly backwards, and presenting some very small processes at
their point of union, but no further trace of a spinous process. The transverse
process, occasionally perforated by a vascular foramen, has an antero-posteriorly thin,
but deep base, which embraces two-thirds of the side of the centrum, sending forwards
a small process from its inferior basal margin. Its upper border, below the
zygapophyses, has a deep intervertebral notch, the inferior outward limit of which
is defined by a small sharp process. The process lies immediately anterior and close
to the transverse process of the axis, but has the superior transverse process of the
fourth vertebra behind and above it. The zygapophyses are on the same level at
the outer end of the laminse, and the two of the right side are of about one size,
but the posterior zygapophysis of the left side is very small.
The fourth vertical has a thin, antero-posteriorly compressed centrum like the
third, but it is relatively higher, its articular surfaces being as high as broad. The
anterior surface is rendered deeply concave in its lower half by the forwardly projecting
inferior transverse processes which are first strongly marked in this vertebra.
The lttmin» are very narrow and rod-like, with a very minute process at their union
and a roughened surface external to it, there being no spinous process. The neural
canal is broadly triangular and not so acutely arched as in the preceding vertebra.
The zygapophyses become more removed from each other, the anterior being at a
lower level than the posterior, and on the right side the two are separated from each
other by a deep notch, while on the left they are closely applied to each other due
to sinistral asymmetry, the left lamina of the neural.arch being also dragged
to the left side. The relative proportions also of the zygapophyses are reversed in
this vertebra from that which prevails in the vertebra before it, the anterior being
about half the size of the posterior zygapophyses. The invertebral notch is not so
broad as in the third, but it is better marked, the equivalent of the process that
defined its inferior outer limit in the latter vertebra is very strongly developed in
this one; and, owing to the shortening of the superior transverse process, it occurs
at its extremity, which is thus bifurcate. The superior transverse process is short
and compressed from before backwards, concave on its superoposterior surface,
bifurcate and directed outwards and slightly backwards, lying below the level of its
fellow behind it and a little above its fellow before it. The base is prolonged down
one-half of the side of the centrum, where it is separated by a semi-circular notch
from the inferior transverse process. The latter has a broad base reaching from the
superior process to the inferior border of the centrum, tapering to a point and
directed forwards, its inferior surface more or less concave, and its superior surface
flat, its anterior surface being grooved. I t is considerably smaller on the left than
on the right side. On the laminse, halfway between the posterior zygapophyses
and their line of union, a small, backwardly-projecting process simulating a hyperapophysis
occurs.
The fifth rpsembles the fourth vertebra in its general form, but the neural arch
is much stronger, and on its left side there is a stout but small backwardly projecting
process like an hyperapophysis ; on the right side this structure is imperfectly developed.
The neural canal is twice as broad as high, but its two halves are unequal,
as the lamina of the right side is depressed. The zygapophyses of the two sides
are unsymmetricai, those of the right having their articular surfaces on nearly the
same plane, separated externally by a very small notch ; while those of the
left are widely apart from each other and smaller than those of the right side.
The transverse process, bifurcate at its extremity, is larger than in the 'preceding
vertebra, and separated by a wider notch from the anterior zygapophyses than'in
the fourth vertebra. This process is posterior and superior to the transverse process
of the fourth vertebra, and lies on the same plane with the superior transverse process
of the sixth. The inferior transverse processes are more strongly developed than in
the fourth, but are considerably smaller than the superior processes.