[LAMBE] PRESIDENTIAL ADDRESS 9 
development and differentiation they form excellent and trustworthy 
horizon-markers. Those from the Judith River rocks include carnivor- 
ous, bipedal Theropoda, and both quadrupedal and bipedal Orthopoda 
or Predentata. The carnivorous dinosaurs of these beds are not so 
numerous nor as well known as the herbivorous ones on which they no 
doubt preyed, but we recognize at least two forms, the large Deinodon 
related to Megalosaurus of the European Jurassic, and Ornithomimus, 
of slender build, supposed to be the descendant of the smaller Jurassic 
Ornitholestes, a rapid moving, cursorial type remarkable, among other 
features, for the apparent, well-developed grasping capability of its 
manus. 
The Orthopoda consist of heavily armoured Stegosauridæ, Cera- 
topside or horned dinosaurs, and duck-billed Trachodontidæ. Of these 
Euoplocephalus is a Stegosaur known from the plated upper portion 
of a cranium, and a transverse arch of solid, keeled scutes which formed 
part of the defensive covering of the neck or tail. This genus was first 
described under the name Stereocephalus (preoccupied) and was 
probably ancestral to Ankylosaurus of a higher horizon in the Cretaceous. 
Two species of Palæoscincus, known from teeth from Red Deer river, 
are doubtfully referred to the Stegosauria. 
The horned dinosaurs belong to the genera Monoclonius and Cera- 
tops and are less specialized and smaller than their apparently direct 
descendants described originally by Marsh from the Laramie of Wyom- 
ing. As has been already suggested this group seems to have had two 
lines of descent, one leading from Monoclonius to Triceratops with an 
entire parietal frill, the other beginning with Ceratops and ending in 
Torosaurus with persistent fenestræ in the crest. As a group the 
Ceratopsia became highly specialized and disappeared at the close of the 
Cretaceous period. We know nothing as yet of the ancestors of the 
Judith River forms. 
Stegoceras is a genus which was at first referred provisionally to the 
Ceratopsia, but whose position is quite uncertain. It was founded on 
cranial fragments, from Red Deer river, which have been interpreted 
as belonging to the occipital, parietal and frontal segments of the skull. 
It has been suggested that Stegoceras may represent a reptilian order 
hitherto unknown, but more material is needed before the homologies 
of the parts of the skull, so far discovered, can be definitely determined. 
Without doubt a reptile new to science is represented by the Red Deer 
river specimens. 
The Trachodontidæ which have lately been proved to have had 
webbed forefeet and therefore adapted to a partial or fully aquatic 
life, are represented by at least three species, viz., Trachodon selwyni, 
