Prof. O. C. Marsh—Restoration of Dinosaurs. 153 
on the nasals. Another feature is the large openings on the side of 
the skull, four in number. The first of these is the anterior nasal 
orifice; the second, the triangular antorbital foramen; the third, 
the large oval orbit; and the fourth, the still larger lower temporal 
opening. 
The parietal bones are of moderate size, and there is no parietal 
foramen. The frontal bones are rather short, and are closely united 
on the median line. The nasal bones are more elongate than the 
frontals, and are firmly codssified. These bones support the com- 
pressed, elevated horn-core on the median line. The lateral surface 
of this elevation is very rugose, and furrowed with vascular grooves. 
It evidently supported a high trenchant horn, which must have 
formed a most powerful weapon for offence and defence. 
The premaxillaries are separate, and each contained three functional 
teeth. The maxillary bones are large and massive, as shown in 
Plate VI. They are provided each with fifteen functional teeth, 
which are large, powerful, and trenchant, indicating the ferocious 
character of the animal when alive. These teeth have the same 
general form as those of Megalosaurus, and the dental succession 
appears to be quite the same. Above the antorbital foramen on 
either side is a high elevation composed of the prefrontal bones. 
These protuberances would be of service in protecting the orbit, 
which they partially overhang. 
The lower jaws of Ceratosaurus are large and powerful, especially 
in the posterior part. In front, the rami are much compressed, and 
they were joined together by cartilage only. There were fifteen 
teeth in each ramus, similar in form to those of the upper jaws. 
The cervical vertebrae of Ceratosaurus differ in type from those in 
any other known reptiles. With the exception of the atlas, all are 
strongly opisthoccelian, the cnp on the posterior end of each centrum 
being unusually deep. In place of an equally developed ball on the 
anterior end, there is a flat surface. The size of the latter is such 
that it can only be inserted a short distance in the adjoining cup. 
This peculiar articulation leaves more than three-fourths of the cup 
unoccupied by the succeeding vertebra, forming, apparently, a weak 
joint. 
The dorsal and lumbar vertebree are bi-concave, with only moderate 
concavities. ‘The sides and lower surface of the centra are deeply 
excavated, except at the ends. All the pre-sacral vertebre are very 
hollow, and this is also true of the anterior caudals. 
There are five well-codssified vertebrae in the sacrum of the present 
specimen of Ceratosaurus nasicornis. ‘The transverse processes are 
very short, each supported by two vertebrae, and they do not meet 
at their distal ends. The caudai vertebra are bi-concave. All the 
anterior caudals, except the first, supported very long chevrons, 
indicating a high, thin tail, well adapted to swimming. The tail 
was quite long, and the distal caudals were very short. 
The scapular arch of Ceratosaurus is of moderate size, but the fore 
limbs are very small. The humerus is short, with a strong radial 
erest. The radius and ulna are also very short, and nearly equal 
