18 
MUSEUM BULLETIN NO. 12. 
It is considered that the species described by Cope under the 
name Monoclonius sphenocerus is allied to Styracosaurus alberten- 
sis and should probably be placed in the latter genus of which the 
Red Deer River species is the type. 
As regards the lately established genus Brachyceratops of 
Gilmore, based on the skull of a young individual from the 
“Upper Cretaceous” of Montana, the writer is of the opinion 
that it includes the species from the Belly River formation, 
Alberta, originally described by him in 1902 under the name 
Monoclonius dawsoni. 
In the three lines of descent through the Eoceratops, Cen- 
trosaurus, and Chasmosaurus groups, salient characters are seen 
in the brow-horns, the nose-horns, and the neck frill. As regards 
the frill, a persistent attempt is seen in all three groups to en- 
large and strengthen it and to render it a more efficient means 
of defence by covering more of the neck and shoulders. 
In the Eoceratops group greater strength was attained by 
the enlargement of. the squamosals and the closing of the fene- 
stra (Plate II), resulting in Triceratops and Diceratops in a 
larger, more compact, and heavier covering to the neck and shoul- 
ders. 
In the Centrosaurus group a larger frill surface is attained 
by an increase in the size of the parietal portion which expands 
behind the squamosals, these latter remaining small (Plate III). 
In Centrosaurus and Styracosaurus, particularly in the latter, 
an increased surface is gained by the addition of bony outgrowths 
which, while not adding to the compactness of the frill, may 
have served a good purpose as defensive weapons or at least 
as an aid to the assumption of a more alarming aspect. The 
fenestrae are smallest, if they have not altogether disappeared, 
in Brachyceratops. 
In the third group, Chasmosaurus leading to Torosaurus 
(Plate IV), the parietal part of the frill lies not so much behind as 
between the greatly lengthened squamosals. The open frame- 
work of the older form (Chasmosaurus) is succeeded by a stronger 
median expansion with comparatively small openings (Toro- 
saurus.) 
