48 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
internal margin sloping obliquely toward the cranium, the external 
more rounded and less declivent. 
The maxillary notch formed by the angle between the apophysis 
or preorbital portion of the supraorbital process of the frontal and 
the adjoining portion of the maxilla is deep and acute. The maxil- 
lary foramina are situated 30 mm.in advance of the maxillary 
notches. 
Posterior view.—As seen from the occipital view (pl. 4) the supra- 
occipital takes the form of a wedge-shaped bone, wider above than 
below. The conspicuous development of the lambdoidal crest is the 
characteristic feature of the back of the skull. Superiorly, the crest is 
formed by the margin of the supraoccipital which abuts against the 
frontals. On the inner sides of the temporal fossae the crest curves 
ventrally and laterally, following the contour of the posterior margins 
of the fossae. 
The exoccipitals are rather large, coalesced with the supraoccipital 
above and projecting outward and backward like wings of the former. 
The external margins are rounded. Laterally and anteriorly they are 
in contact with the squamosals, while below they are fused internally 
with the basioccipital. The sharp-edged lambdoidal crest overhangs 
the exoccipitals on either side. 
The opening for the foramen magnum was originally circular. The 
occipital condyles are semielliptical in outline with their long axes 
directed dorso-ventrally. They are strongly convex from side to side. 
The internal margins are concave and sharply defined, converging 
inferiorly. The external margins of the condyles are not set off from 
the exoccipitals by shallow concavities, but gradually merge into the 
exoccipitals. Ventral to the condyles and internal to the exoccipitals 
are the descending free plates of the basioccipital. Ventral to the 
temporal fossae and external to the exoccipitals are the large squa- 
mosals and their zygomatic processes. 
Lateral view—The lateral aspect (pl. 3) of the rostrum is formed 
almost entirely by the maxilla, though the tip was presumably made 
up by the premaxillae alone. The thickness of the broken anterior 
edge of the maxilla indicates that it extended some distance farther 
forward, how far, can only be surmised by comparison with other 
described forms. This view best illustrates the upturning of the ante- 
rior half of the rostrum which imparts a peculiar bowed appearance 
to the superior outline of the skull. 
The skull as a whole is rather slender, and the height at the vertex 
is proportionately low in comparison with that of the base of the ros- 
trum. A large alveolar gutter, with the septa between the alveolae 
formed of porous bone, terminates 62 mm. in advance of the maxil- 
lary notch. The supraorbital process of the frontal is concave above 
and below. The preorbital process or apophysis is rounded; the post- 
orbital process is abruptly truncated and sharp edged. 
