19 
Parietal (P.)* Figures 3, 4, 3, 6, 8, and 26. This bone, the coalesced 
parietal pair, forms the roof of the brain-case from behind the cerebrum 
to the cerebellum, and, in the upper surface of the skull, passes backward 
from the frontals to the squamosals, separating; the supratemporal fossje. 
The parietal is longer than broad, narrow for a considerable distance in 
front of and behind its midlength, and expanded outwardly about equally 
at either end. Medially it rises between the supratemporal fossae, with an 
increasing amount of lateral compression, to the plane of the upper surface 
of the skull as a high interfossate ridge extremely narrow above. Its 
lateral faces within the fossae are concave from below upward. 
Supero-anteriorly the parietal meets the frontals to the full extent 
of their combined posterior breadth in a zigzagged, transverse suture. 
Antero-externally it is in contact with the postfrontals in a short suture 
which, leaving the upper surface of the skull, passes down the front margin 
of the supratemporal fossa and runs forward for a short distance on the 
lower border of the same. Figure 5, P. Posteriorly it meets the squamosals 
from below in a curved transverse suture about half-way up the posterior 
face of the supratemporal fossa. In continuation of its median ridge it 
passes back narrowly, to the occiput separating the squamosals. The 
upper surface of this intersquamosal portion lies in the general plane of 
upper surface of the skull and is longitudinally channelled. 
The parietal connects interiorly with the alisphenoid in front, with 
the prootic farther back, and with the exoccipital behind. The sutural 
line marking the contact of the lower border of the parietal with the ex- 
occipital and prootic runs forward horizontally in the floor of the supra- 
temporal fossa. Its anterior continuation as the parieto-alisphenoid 
suture rises with an outward curve and terminates at the postfrontal a 
short distance in advance of the anterior margin of the supratemporal 
fossa, see Figure 5, P — Als. 
The parietal posteriorly in its outward curve within the supratemporal 
fossa, at a lower level than the squamosal, enters largely into the formation 
of the posterior face of the opening. Interiorly it assists the exoccipital, 
prootic, and alisphenoid in providing a partial floor to the opening. With 
a small external contribution from the postfrontal it bouncls the opening 
in front. 
A narrow, distinctly marked groove, continuous along the summit of 
the interfossate ridge, apparently marks the original division of the parietal 
pair. 
Measurements of Parietal of Specimen, Cat. No. 2289. 
Length along the niidline above 
Maximum anterior breadth within the supratemporal fossa' 
Maximum posterior breadth 
Height at midlength 
Breadth at midlength 
Mm. 
198 
150 
148 
57 
62 
Squamosal (Sq.). Figures 3, 4^ und 8. This bone is large 
and with its fellow forms almost the whole of the hinder part of the upper 
surface of the skull. It bounds the supratemporal fossa posteriorly, 
enters largely into the formation of the external border of the same, and 
is in contact with the parietal, postfrontal, quadrate, exoccipital, and 
?8upra-occipital. It is broadest behind, and medially in front extensively 
