33 
The inverted bony arch for the protection of the carotid arteries is first seen to be de- 
veloped from the inner side of the inferior transverse processes of the twelfth cervical 
vertebra, but the two sides of the arch are not anchylosed together ; the interspace pro- 
cressively increases in the eleventh, tenth, and ninth vertebra, and the groove widens and 
is lost at the fifth vertebra. The spinous process is thick and strong in the vertebra dentata, 
but progressively diminishes to the seventh cervical vertebra, where it is reduced to a mere 
tubercle ; from the eleventh it progressively increases to the last cervical, in which it pre- 
sents the strong quadrate figure which characterizes the same process in the dorsal vertebre. 
The large canal on each side for the vertebral artery and sympathetic nerve is formed 
by the anchylosis of a rudimental rib to the extremities of an upper and lower transverse 
process ; the costal process diminishes in size in the anterior cervical vertebra: it is 
wanting in the dentata, though an arterial canal of very small size is present on each side 
of that vertebra. In the atlas there are two small inferior transverse processes, but no 
canal, The superior or neurapophysial bony arch increases in extent as the cervical 
vertebre approach the head, and in the third, fourth, and fifth vertebre this part is per- 
forated by a small foramen on each side. The spinal chord is least protected by the 
vertebre in the middle of the neck, where there is the greatest extent of motion: there 
is a depression on the anterior and posterior parts of the spine in the second, third, 
fourth, and in the last six cervical vertebre. 
The length of the cervical region of the spine is 7 inches. 
The close resemblance of the Bird to the Reptile in its skeleton is well exemplified in 
the young Ostrich, in which even when half-grown the costal appendages of the cervical 
region of the vertebral column continue separate and moveable, as in the Crocodile. I 
have already observed that they were anchylosed to the first fifteen vertebre in the 
Apteryx. The first dorsal rib is a slender style about an inch in length ; the rest are re- 
markable for their breadth, which is relatively greater than in any other bird ; the Casso- 
wary in this respect approaches nearest to the Apterya. The second, third, fourth, and fifth 
ribs articulate with the sternum through the medium of slender sternal portions ; that of 
the sixth also reaches the sternum, but is attached only to the sternal rib anterior to it, 
and a considerable interspace exists between its unattached extremity and that of its cor- 
responding vertebral rib. In the first simple and floating rib, the part corresponding to 
the head and neck, as usual, is not developed, and it is attached to the transverse pro- 
cess by the part analogous to the tubercle. Inthe second rib a short and strong cervix, 
terminated by a hemispherical head, is given off below and in front of the tubercle, and 
works in a corresponding socket at the anterior margin of the vertebra. The head and 
tubercle, with the points of the vertebre to which they are attached, intercept large 
foramina corresponding to the vertebral foramina in the cervical region, Immediately 
below the tubercle the rib suddenly expands, and then gradually narrows to its lower 
end: the neck of the rib increases in length in the third and fourth pairs and dimi- 
nishes in the last two ; the sixth rib begins to lose its breadth, and the rest become nar- 
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