794 REPORT—1890. 
’ 
two or three orders and several families. Plesiosaurs, crocodiles, aud turtles of 
cretaceous types, and many smaller reptiles, have left their remains in the same 
strata. Numerous small mammals, also of ancient types, a few birds, and many 
fishes, are likewise entombed in this formation. Invertebrate fossils and plants 
are not uncommon in the same horizon. 
The skull of Triceratops, the best known genus of the family, has many re- 
markable features. First of all its size, in the largest individuals, exceeds that of 
any land animal, living or extinct, hitherto discovered, and is only surpassed by 
that of some of the Cetaceans. The skull, represented natural size in one of the 
diagrams shown, was that of a comparatively young animal, but is about six feet in 
length. The type of Triceratops horridus was an old individual, and the head, 
when complete, must have been nearly eight feet in length. Two other skulls, 
both nearly perfect, were also represented by life-size sketches, and others from 
the same horizon have equal dimensions. 
Another striking feature of this group is its armature. This consisted of a 
sharp cutting beak in front, a strong horn on the nose, a pair of very large pointed 
horns on the top of the head, and a row of sharp projections around the margin of 
the posterior crest. All these had a horny covering of great strength and power. 
For offence and defence they formed together an armour for the head as complete 
as any known. This armature dominated the skull and in a great measure deter- 
mined its form and structure. 
The skull itself is wedge-shaped in form, especially when seen from above. The 
facial portion is very narrow and much prolonged infront. In the frontal region 
the skull is massive and greatly strengthened to support the large and lofty horn- 
cores which formed the central feature of the armature. The huge expanded 
posterior crest which overshadowed the back of the skull and neck was evidently 
of secondary growth, a practical necessity for the attachment of the powerful 
ligaments and muscles that supported the head. 
The brain of Triceratops appears to have been smaller in proportion to the 
entire skull than in any known vertebrate. Its position and relative size were 
shown in a diagram. The position of the brain in the skull does not correspond to 
the axis of the latter, the front being elevated at an angle of about thirty degrees. 
The teeth of Triceratops and its near allies are very remarkable in having two 
distinct roots. This is true of both the upper and lower series. These roots are 
placed transversely in the jaw, and there is a separate cavity, more or less distinct, 
for each of them. One of these teeth was represented by an enlarged figure and 
another tooth was itself exhibited. The teeth form a single series only in each 
jaw, but the grinding surface is reversed, being on the inner side of the upper series 
and on the outer side of the lower series. 
The atlas and axis of Triceratops are co-ossified with each other, and at least 
one other vertebra is firmly united with them. These form a solid mass well 
adapted to support the enormous head. The remaining cervical vertebrae are 
short and have the articular faces of the centra nearly flat. 
The trunk vertebrae have very short centra with flat articular ends. The 
posterior trunk vertebre have diapophyses with faces for both the head and 
tubercle of the ribs, as in crocodiles. The sacrum was strengthened by union with 
several adjacent vertebr, ten in all being co-ossified in one specimen of Triceratops. 
The caudal vertebr are short and rugose, and the tail was of moderate length, 
The ilium is elongated and massive and the front portion more expanded than 
the posterior. The ischium is slender and curved inward and backward. The 
pubis extends forward and its distal end is much expanded. Its posterior branch 
is wanting. 
The limbs were short and massive and all four were used in locomotion. The 
feet were all provided with broad hoofs. All the bones of the skeleton appear to 
have been solid. Dermal ossifications were present and some species were protected 
by armour. 
The main characters which separate the Ceratopside from all other known 
families of the Dinosauria are as follows: 
1. A rostral bone forming a sharp cutting beak. 
