18 THE SKELETON OF THE CAT. 
cates here with the capsule of the atlanto-occipital articulation. 
In the dorsal part of the capsule a short 
strong ligamentous strand is developed, 
connecting the caudal border of the dorsal 
, arch of the atlas with the tip of the 
‘“2)\ cranial projection of the spinous process 
' of the axis. 
The dens or odontoid process is 
held in place by the transverse liga- 
ment (Fig. 14, 4) of the atlas, which 
passes across the process as it lies with- 
in the vertebral canal of the atlas. The 
transverse ligament is attached at its 
Fic. 14.—LIGAMENTS OF 
THE ODONTOID PROCESS 
or DENs. two ends to the medial surface of the 
First three cervical ver- .; ; 
tebrseand baseof theskull, sides of the atlas at about the region 
with dorsal surface re- where the dorsal and ventral arches of 
moved. a, ligamentum the atl 1 
longitudinale posterius; 4, “HE alias unite. 
transverse ligament of the From the cranial end of the odontoid 
atlas; ¢, ligamenta alaria; li t lav Fi 
d, odontoid process; ¢, oc. Process the two ligamenta alaria (Fig. 
cipital condyles; 1, 2, 3, 14, c) diverge craniolaterad to the rough 
the first three cervical ver. 4, ¢) ; 8 8 
tebrze; 4, basal portion of ventromedial angle of the condyles of 
theierpial bone: the occipital bone. 
II. RIBS. COSTA. (Figs. 1 and 15.) 
The cat has thirteen pairs of ribs. One of the fifth pair 
(Fig. 15) may be taken as typical. It is a curved flattened rod 
of bone attached at its dorsal end to the vertebral column, 
and at its ventral end to a cartilage (costal cartilage, Fig. 
15, /) which serves to unite it to the sternum. 
The most convex portion of the bone is known as the 
angle (e). Each rib presents a convex lateral and a con- 
cave medial surface, a cranial and a caudal border. The 
borders are broad dorsad and narrow ventrad, while the sur- 
faces are narrow dorsad and broad ventrad. The rib has thus 
the appearance of having been twisted. 
The rib ends dorsad in a globular head or capitulum (a), 
by which it articulates with the costal demifacets of two con- 
tiguous thoracic vertebree. Between the capitulum and angle 
