24 THE SKELETON OF THE CAT. 
Laterad of each condyle the bone is elevated into a blunt 
triangular projection, the jugular process (7), which covers the 
caudal end of the tympanic bulla. Between the jugular process 
and the condyle is a deep depression. : 
The internal surface (Fig. 18) is concave dorsoventrally, 
following the outline of the foramen magnum. It is convex 
from side to side. It is smooth except at its outer margin, 
which is rough for articulation with the mastoid portion of the 
temporal bone. The cranial face of the jugular process (/) 
shows a rough concavity for the reception of the bulla tympani. 
Mediad of the jugular process is a notch (jugular notch) (¢) 
which when the bones are articulated forms part of the bound- 
ary of the jugular foramen. Mediad of this notch is a foramen 
which forms one end of the hypoglossal canal. It passes dorso- 
caudad into the cranial cavity and transmits the hypoglossal 
nerve. Dorsad of the hypoglossal canal is the cranial opening 
of the condyloid canal, which passes caudad and opens just 
craniad of the dorsal end of the condyle. It transmits a vein. 
The outer border of this portion is rough for articulation with 
the petrous and mastoid portions of the temporal. 
The squamous portion (c) has the form of a sector of a 
circle whose arc is a little more than ninety degrees. The 
central angle of the sector is truncated and bounds the foramen 
magnum dorsally. The arc of the sector forms the dorsal 
margin of the bone, while along the radii it passes into the 
lateral portions. Its dorsal portion is thick and porous; its 
ventral portion near the foramen magnum is thin and compact. 
The external surface (Fig. 17) is marked by a prominent 
ridge, the lambdoidal ridge (4), parallel with the dorsal border 
and near to it. The narrow portion of the outer surface that 
lies dorsad of the ridge forms an angle of about ninety degrees 
with the remainder’ of the surface. 
A median crest (2) extends ventrad from the middle of the 
lambdoidal ridge toward the foramen magnum; this~ is the 
external occipital crest. At its junction with the lambdoidal 
ridge it is elevated into a tubercle, the external occipital 
protuberance (7). 
