DOUGLASS; THE TERTIARY OF MONTANA 217 
On the top of the skull on the anterior portions of the frontals are two oblong con- 
vexities extending backward from the anterior points of these bones and slightly 
diverging posteriorly. Between these along the frontal suture is a longitudinal con- 
cavity. The posterior portions of the frontals are flat or slightly concave. The 
greater portion of the parietals is broken away showing a cast of the brain-case. On 
the frontal the supra-temporal ridges are hardly distinguishable. On the posterior 
portion of the parietals they can be plainly seen. They are a considerable distance 
apart but converge slightly forward. The parieto-temporal suture is nearly hori- 
zontal. ‘There are no post-orbital processes and the post-orbital constriction is slight. 
Ictops intermedius sp. nov. 
arnegie Museum Collection, No. 1019. 
This species is represented by the skull of an old individual with the lower jaw. 
The snout is gone, but it isin part restored in plaster from the impression on the 
rock. It was found in the same beds with Ictops tenws to be described later, though 
at a little higher level, in the Titanotherium Beds of McCarty’s Mountain, north of 
Dillon, in Montana. 
PrincipaL CHaracters. — The skull is smaller than that of Ictops montanus and 
less robust. Though the skulls are similar throughout, yet there are differences, either 
slight or more pronounced in nearly every part. The most noticeable are the following : 
In I. intermedius the zygomatic arches are much more slender, the post-glenoid processes 
smaller and shorter, the mastoid process does not extend downward so far and is entirely 
different in form, the posterior portion of the skull is narrow, and the foramen magnum 
smaller. The teeth are shorter antero-posterrorly but fully as wide. 
DETAILED COMPARISON. 
The upper teeth are too much worn for accurate comparison. 
The Skull. — Measuring from the anterior of P+ to the occipital condyles this 
skull is 90 per cent. of the length of that of I. montanus. 'The width at the post- 
glenoid processes is 86 per cent. The width of the occiput nearly 82 per cent., the 
depth of the anterior portion of the zygomatic arch 71 per cent., and of the posterior 
66 per cent. The occipital region besides being smaller was apparently more con- 
vex, but it is somewhat injured in the present specimen so one cannot be sure. The 
palate views of the skulls are much alike, except in the size of the different parts. 
The depression at the anterior portion of the zygomatic arch is much shallower than 
in J. montanus, or in I. tenwis, which are described in this paper. The zygomatic 
arch is slenderer than in any other specimen I have examined except, perhaps, 
