80 
The postorbital process is long and slender and in its upper portion 
overlaps, anteriorly, the inner border of the descending postorbital process. 
That is, it is internal to the postorbital pocket, thus making it within the 
orbit and well removed from the exterior of the skull. Anteriorly the 
jugal sends a process forward which wedges in between the lachrymal 
and maxilla and comes in contact with the posterior portion of the lower 
limb of the premaxilla. Antero-superiorly a small, tongue-like process 
extends upward, and fits into a groove on the infero-external surface of 
the lachrymal, thus giving great strength to this union, and internal to this 
contact it unites with the anterior border of the palatine. 
The exact shape of the foramen magnum can not be determined, due 
to its distortion by lateral crushing. It is bounded below by the basi- 
occipital; laterally, and apparently superiorly, by the exoccipitals. View- 
ing the skull from behind, the foramen magnum is set deeply in the occiput 
with the exoccipitals extending upward and backward, thus making a 
large overhang much as in Edmontosaurus. 
The occipital condyle is roughly U-shaped, the sides being formed by 
the exoccipitals and the base by the robust basioccipital. These elements 
are well preserved and the sutures separating them are clearly distinct. 
The basioccipital is a thick bone and is in contact superiorly with the 
exoccipitals and anteriorly with the basisphenoid. It forms the base 
of the occipital condyle, contributing more than one-half of its articulating 
face. Inferiorly it is very rugose. Superiorly it is encroached upon by 
the exoccipitals, contributing only slightly to the floor of the brain cavity. 
The exoccipitals bound the foramen magnum laterally and superiorly 
and contribute to the formation of the occipital condyle. There is no 
indication of the supraoccipital separating the exoccipitals at the superior 
border of the foramen magnum, but apparently the exoccipitals unite 
and form the whole of the superior border of the opening and roof over 
the occipital region. On the inferior surface of this roof, at the midline, 
is a ridge which possibly represents the co-ossified union of the exoccipitals. 
On the superior surface of the united exoccipitals is a thick, broad, ridge 
of bone which has the appearance of a separate ossification. This probably 
represents the supraoccipital. This is much the condition found in the 
badrosaurian cranium figured by Brown, from the Edmonton formation . 1 
The suture between the exoccipital and opisthotic is not discernible 
and the one between the exoccipital and alisphenoid is only faintly indicated. 
There is no indication as to the limits of the epiotic or prootic. The suture 
between the alisphenoid and basisphenoid is well shown, and proves, as 
in Lambeosaurus lambei ( Stephanosaurus marginatus) 2 that the flange above 
and slightly behind the basisphenoid process is a part of the basisphenoid. 
The cranial foramina are well shown on the right side of the brain 
case. They closely resemble, both in form and position, those of the 
brain case of the hadrosaur from the Edmonton formation figured by 
Brown®. The only difference of note being, that the exit for the seventh 
nerve is not divided by a transverse bridge of bone, but the lower division 
passes downward, on the side of the brain case in a shallow, open channel, 
and the foramina are not located at the bottom of well-marked depressions. 
1 Brown, B.: “Anchiceratope; a New Genus and Species of Horned Dinosaur from the Edmonton Cretaceous 
of Alta.”; Am. Mus. of Nat. Hist., Ext. Bull., vol. XXXIII, p. 545 (1914). 
* Geol. Surv., Canada, Kem. 120, p. 76. 
*liOC.cit. 
