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DES. A. CAETE AND A. MACALISTEE ON THE 
physial disks of two vertebrae were distinctly visible, separated from each other by a 
rudimental articular surface, thus bearing out the theory promulgated by Professor 
Owen, that the central elevation of the axis vertebra is in reality the homologue of the 
centrum or body, not of this segment, to which it would now seem to belong by osseous 
coalescence, but of the atlas. This theory is further evidenced by the fact that the 
odontoid process appears to have three points of ossification ; first, a small irregular de- 
tached piece of bone imbedded in the apex of the elevation, and which represents the 
upper epiphysial disk of the atlas ; secondly, a point of ossification, but much larger, in 
fact forming the greater part of the odontoid process, and coalescing anteriorly and 
laterally with the upper surface of the axis ; and thirdly, a small flat thin plate which 
formed the upper boundary of the transverse fissure, before noticed as existing in the 
posterior wall of the body or centrum of the bone. 
Surrounding the hemispherical eminence, there was a crescentic-shaped depression, 
which received the posterior articular surfaces of the atlas. 
The posterior surface of the body of the axis was concave, and in outline irregularly 
elliptical ; it was slightly grooved posteriorly. The neurapophyses arched backwards 
and terminated in a bifid neural spine, which was more robust than that of the atlas. 
The oblique or articular processes (zygapophyses) were small, with nearly circular facets 
situated towards the bases of the neurapophyses, with their articular surfaces directed 
backwards, downwards, and inwards. The diapophyses were large and robust, and pro- 
jected from the sides of the centrum. The pleurapophyses were also well developed, 
and, together with the diapophyses, formed nearly three-fourths of an oval, which in the 
recent state was completed by interposed cartilage ; the spaces thus enclosed in this 
vertebra measured about If inch in diameter. 
The remainder of the cervical vertebrae were in outline somewhat similar to the axis, 
but their bodies were much more compressed in the antero-posterior direction. Their 
parapophyses extended from the sides of the anterior portions of each centrum forwards 
and outwards, diminishing in length to the seventh or last cervical, where they were merely 
rudimental. The lateral processes (diapophyses) were much longer but less robust 
than the parapophyses, and those of the third, fourth, and fifth were directed backwards, 
while the other two arched forward from the bases of the neurapophyses ; these, in con- 
j unction with the parapophyses anteriorly and sides of the centrum, internally formed 
an oval-shaped space, which in the recent state was completed by fibrocartilage uniting 
the extremities of the parapophyses to those of the diapophyses. The zygapophyses 
resembled both in shape and position those of the axis. In consequence of the lateral 
extension of these processes, motion in the cervical region was greatly restricted ; this, 
however, when we take into consideration the economy of the animal, was of little mo- 
ment as compared to the protection afforded by these bony arches to the important vas- 
cular sinuses, which in the recent state were lodged in these cavities on each side of the 
neck, and which were formed by the interlacement of numerous vessels from the verte- 
bral and carotid arteries, inosculating freely with each other and producing a beautiful 
example of a rete mirabile. 
