88 MEMOIRS OF THE CARNEGIE MUSEUM 
gated suture, this part inferiorly meets the supratemporal and the posterior por- 
tion of the postfrontal. The squamosal as in Reptilia and Batrachia generally 
forms part of the combination which supports the quadrate. This bone articulates 
with the quadrate, parietal, opisthotic, supratemporal and postfrontal. 
MEASUREMENTS. 
No. 878. Greatest length of anterior branch of squamosal 
“SG Sesh a os internal ‘‘ a 
‘C878. ce “c inferior 66 oe 
Supratemporal (s.t.).—The supratemporal is an irregular subtriangular bony 
plate that is wedged into the interspace between the squamosal, post-frontal, post- 
orbital, quadratojugal and quadrate. Externally the surface is slightly convex. 
This bone represents the prosquamosal or swpersquamosal of Owen, the temporal of 
Cuvier, the squamosal of Baur and Merriam, and the swpraquadrate of Seeley; the 
latter name being given because it rests upon and hides from lateral view the upper 
portion of the quadrate. The terms enumerated have been used in describing 
the more primitive forms contained in the genera Shastasawrus and Ichthyosawrus. 
Quadrate (qu.).— The quadrate viewed posteriorly is a flat narrow vertical plate 
with the external margin excavated. In conjunction with the quadratojugal it 
enclosed the auditory opening as in Sphenodon. Superiorly this element meets the 
supratemporal and squamosal, the latter assuming the greater part of the articula- 
tion as will be found to be the case in most of the Ichthyosaurs. The quadrate ex- 
pands distally into a heavy transverse articulation for the lower jaw. ; 
In specimen No. 878 the lateral separation between the quadrate and inferior 
branch of the squamosal is distinetly shown on both sides of the skull, see Pl. XL, 
fig. 1, but on the left side of the skull of No. 603 the suture has become obliterated 
and the two bones thus united form a continuous broad plate of bone. Distally 
the external concave border turns abruptly outward. It is upon this border just 
internal to the articular end that the infero-posterior angle of the quadratojugal rests. 
The lower internal border of the quadrate unites closely with the postero-lateral 
process sent off by the pterygoid. On the lower posterior surface there is a slightly 
roughened groove which received the lower or distal end of the stapes. ‘These ele- 
ments have been somewhat displaced by crushing, and their normal relations can- 
not be definitely determined, though the presence of this groove has convinced the 
writer that the above was undoubtedly their natural position. See Pl. XI., fig. 2. 
Specimen No. 603, which has the posterior portion of the right ramus wanting, 
gives a good view of the articular end of the quadrate. It is pentagonal in form, 
