154 Prof. O. C. Marsh—Restoration of Dinosaurs. 
in size. The carpal bones were only imperfectly ossified. There 
were four digits in the fore foot, and all were armed with sharp 
claws. The second and third digits were much larger than the first 
and fourth, and the fifth was entirely wanting. 
The pelvic arch of Ceratosaurus is of special interest. In the 
type specimen here restored, the ilium, ischium, and pubis, on each 
side, are firmly coéssified. The ilia, moreover, are attached to the 
sacrum, which was in place in the skeleton. The ilia have the 
same general form as in Megalosaurus. The ischia are comparatively 
slender. They project well backward, and for the last half of their 
length the two are in close apposition. Their distal ends are 
codssified and expanded, as shown in Plate VI. 
The pubes have their distal ends codssified, and expand into an 
elongate, massive foot, which is one of the most characteristic parts 
of the skeleton. It is probable that this foot in connection with the 
distal ends of the ischia served to support the body in sitting down. 
That some Triassic dinosaurs sat down on their ischia is proved 
conclusively by the impressions in the Connecticut river sandstone. 
In such cases, the leg was bent so as to bring the heel to the ground. 
The same action in the present reptile would bring the foot of the 
pubes to the ground, nearly or quite under the centre of gravity of 
the animal. The legs and ischia would then naturally aid in keeping 
the body balanced. Possibly this position was assumed habitually 
by these ferocious biped reptiles, in lying in wait for their prey. 
The femur is much curved, and the shaft very hollow. The tibia 
is shorter than the femur, nearly straight, and has a large cnemial 
crest. ‘The astragalus is not codssified with the tibia, and has a 
strong ascending process. ‘The fibula is well developed, and nearly 
straight, its distal end fitting into the caleaneum. ‘The tarsals of 
the second row are very thin, and united to the metatarsals below 
them. 
The most interesting feature in the extremities of this dinosaur 
is in the metatarsal bones, which are completely ankylosed, as are 
the bones of the pelvis. There are only three metatarsal elements 
in each foot, the first and fifth having apparently disappeared 
entirely. The three metatarsals remaining, which are the second, 
third, and fourth, are proportionally shorter and more robust than 
in the other known members of the Theropoda, and being firmly 
united to each other, they furnish the basis for a very strong hind 
- foot. The phalanges of the hind feet are of moderate length, and 
most of them are quite hollow. The terminal phalanges evidently 
supported strong and sharp claws. 
The unique cervical vertebra, the codssification of the pelvic 
bones, and the union of the metatarsals, as in modern birds, dis- 
tinguish Ceratosaurus widely from all other dinosaurs, and make it 
the type of a well-marked family, the Ceratosauride. The nearest 
allied form is apparently Ornithomimus, from the Laramie, recently 
described by the writer. 
The type specimen of Ceratosaurus was about twenty-two feet 
long when alive, and twelve feet high as here restored. It was 
