Cope.] 524. (Jan, 15, 
The side is divided by the gentle convexity continued forwards from. the 
malar region. Below this and above the premolars the face is concave. 
Above it the preorbital fossa is well marked, though not deep, and gradu- 
ally fades out anteriorly, The-interorbital region is flat, as in J. macroste- 
gvs, and the supraorbital border is not decurved, as it is in I, swperdus and 
M. montanus. The supraorbital and preorbital borders of the front are, 
however, not continuous as in M. macrostegus, though: nearly in the 
same line, which they are not in JZ syperbus. The orbits are more oblique 
than in I, superbus, looking more upwards)and forwards, and their verti- 
eal. exceeds their transverse diameter. Themalar bone though oblique, is 
more vertical than the orbit below the latter, ‘and has an uninterrupted 
gently concave surface. The postorbital bridge is narrow, and consists 
one-half of the malarand one-half of the frontal bones. The inferior edge 
of the malar is thin and is slightly convex downwards, and passes behind 
the protuberant squamosal at-a point behind the line of the postfrontal pro- 
cess. The anterior extremity of the squamosal is not protuberant below the 
orbit and only begins to rise gradually below the line of the postfrontal 
process. It then expands rapidly downwards and outwards in a strong 
curve, with its flat surface looking upwards as much as outwards. After 
making a short downward turn it rises steeply, contracting gradually in- 
wards, and presenting a convexity posteriorly, with its truncate edge 
looking outwards. Its apex is nearly on a level with the sagittal crest. 
The inner or descending edge of this process is concave, so that the apex 
overhangs a little the posterior outlet of the temporal fossa. The anterior 
temporal angles are strongly marked and unite into a sagittal crest. The 
edge of\ the crest is thickened, so that its section is a letter T. 
The supraoccipital bone presents a wide flat convexity above the foramen 
magnum, in distinction from the stronger convexity of MZ. superbus, and 
the still stronger of the IZ macrostegus and M. montanus. As in the other 
species, the posttemporal (= lateral occipital) crests are only present 
at the upper half of the occiput. Between them there are two ligamen- 
tous or tendinous insertions, but no median keel. The exoccipital and 
posttympanic borders form a tuberosity below the meatus auditorius, which 
passes upwards into a short convex posttemporal crest. ‘The paroccipital 
process nearly reaches the postglenoid by its anterior external edge. The 
tympanic is complete, is not keeled below, and extends itself as a lamina 
over the posterior side of the postglenoid process. The section of the 
basioccipital is open V-shaped. The inferior flat surface of the sphenoid 
is produced backwards in a wedge-shaped prominence to a line connect. 
ing the anterior edges of the paroccipital processes, It has the same form 
in MU. macrostegus, but in three skulls of IL superbus, where it is visible, 
the apex of the wedge does not extend posterior to the middle of the otic 
bulle. The bulle are small and subconical, and reach as far as the ante- 
rior edge of the postglenoid process. In the latter the transverse diam- 
eter exceeds the anteroposterior, which exceeds the vertical diameter. 
This process and the otic bulla are of about equal protuberance. In four 
