30 THE SKELETON OF THE CAT. 
optic foramen (c). Caudad of this foramen the surface presents 
an oblique groove which forms in the natural condition the 
medial boundary of the orbital fissure. 
Craniad of the optic foramen the surface is smooth and 
marked near its ventral border by a longitudinal ridge which 
forms part of the dorsal boundary of a fossa, the external ptery- 
goid fossa (Fig. 40, f). 
The caudal end presents ventrally a quadrangular rough . 
surface for articulation with the body of the sphenoid. The 
cranial end presents the two apheanical s: sinuses separated by 
a median partition. 
The median partition articulates by its free border with the 
lamina perpendicularis of the ethmoid. At its ventral end is 
the abruptly truncate end of the median ridge of the ventral 
surface, which is continuous with the ventral cartilaginous por- 
tion of the lamina perpendicularis. The lateral walls of the 
sphenoidal sinuses are continued craniad of the dorsal and ven- 
tral walls and of the median partition, and articulate ventrally 
with the nasal portion of the palatine bones, and dorsally with 
the orbital plate of the frontal. Between them is received the 
caudal ends of the labyrinths of the ethmoid in the middle, 
while between their dorsal edges is received the caudal end of 
the cribriform plate, and between their ventral edges the 
expanded end of the vomer. 
The wings (4) arise each from nearly the whale of the 
dorsolateral angle of the body. They form prominent nearly 
horizontal triangular projections over the optic foramina. 
The dorsal and ventral surfaces are smooth and continuous 
respectively with the dorsal and lateral surfaces of the body. 
The dorsal surface looks into the cranial cavity, while the ven- 
tral looks into the orbitotemporal fossa. 
Craniad of the apex of the wing its border articulates with 
the ventral edge of the orbital portion of the frontal bone. 
Caudad of the apex the border articulates with the cranial 
border of the wing of the sphenoid. 
Temporal Bone. Os temporale (Figs. 22 and 23).—This 
forms a part of the lateral wall of the cranium, filling the gap 
between the occipital and the sphenoidal segments. It is made 
