BONES OF THE SKULL—CRANIUM 189 
The interparietal bone fuses with the occipital before birth. It bears the high 
posterior part of the parietal crest, and is wedged in between the two parietal bones. 
It forms the central part of the tentorium osseum, which is thin and curved, con- 
cave ventrally. Its base concurs with the occipital and parietal bones in the for- 
mation of a transverse canal which is continuous with the temporal canals. 
The parietal bone is rhomboid in outline and is strongly curved. It is exten- 
sive and forms the greater part of the roof of the cranial cavity. At the junction 
of the right and left bones there is a prominent parietal crest which is continued 
upon the frontal bones. The ventral border articulates with the temporal wing 
of the sphenoid by its anterior part and with the squamous temporal in the remain- 
der of its extent. The external surface enters into the formation of the temporal 
Fic. 208.—SktLt oF Dos; LaTerat VIEW, 
A, Occipital bone; B, pgrieta! bone; C, squamous temporal bone; D, frontal bone; E, lacrimal bone; F, nial 
bone; G, perpendicular part of palatine we H, maxilla; I, premaxilla; J, nasal bone; K, mandible; 1, parietal 
“crest; 2, occipital~condyle; 3, paramastoid process; 4, stylo-mastoid foramen; 5, bulla ossea; 6, meatus acusticus 
externus; 7, external opening of temporal canal; 8, postglenoid process; 9, zygomatic process of temporal bone; 10, 
zygomatic process of malar bohe; 11, supraorbital process; 12, entrance to lacrimal canal; 13, infraorbital foramen; 
14, mental foramina; 15, condyle of mandible; 16, coronoid process; 17, mandibular notch; 18, angular process; 19, 
masseteric fossa; i. i’, incisor teeth c, c’, canine teeth. 
fossa. The cerebral surface is marked by digital impressions, and by grooves for 
the middle meningeal artery and its branches. 
The external surface of the frontal bone is crossed by a frontal crest, which 
extends in a curve from the parietal crest to the supraorbital process, and separates 
the frontal and temporal parts. The frontal parts of the two bones form a central 
depression and slope downward and forward. The supraorbital process is very 
short, so that the supraorbital margin is incomplete as in the pig.. The supraor- 
bital foramen is absent. In front there is a narrow pointed nasal part which fits 
in between the nasal bone and the maxilla. The orbital and temporal parts are 
relatively extensive. Two ethmoidal foramina are commonly present. The 
frontal sinus is confined to the frontal bone. 
The parts of the temporal bone fuse early. The zygomatic process curves 
widely outward and forward. Its anterior part is beveled ventrally and articulates 
