' partially overlying the orbits, which they 
May 2, 1884.]° SCIENCE. 543 
The facial portion is elongate, tapering gradually forms found with them. Some facts seem to indi- 
to the muzzle. Seen from above, the skull in out- cate that they were viviparous. The pubes were 
Pelvis of Ceratosaurus nasicornis Marsh; side view, seen from the left. 
a, acetabulum; 7@/,ilium; zs, ischium; p, pubis. One-twelfth natural 
size. 
Skull of Ceratosaurus nasicornis Marsh ; 
front view. 
line is like that of a crocodile; seen from the side, long, and firmly united for the greater part of their 
it appears lacertilian in type, the general struc- length, terminating below in a large, massive, foot- 
ture being light and open. The nasal 
bones support a large, compressed, elevated 
horn-core on the median line. It evident- 
ly supported a high trenchant horn, which 
must have formed a powerful weapon for 
offence and defence. The maxillary bones 
are large and massive, as are also the lower 
jaws. They are each provided with nu- 
merous teeth, which are large, powerful, 
and trenchant, indicating clearly the fero- 
cious character of the animal when alive. 
There are, moreover, large protuberances 
doubtless served to protect. The brain 
was of medium size, but comparatively 
much larger than in the herbivorous dino- 
saurs: it was quite elongate, and situated 
obliquely in the skull. The foramen mag- 
num is small. The cerebellum was of 
moderate size. The optic lobes were well 
developed, and proportionally larger than 
the hemispheres. The olfactory lobes were 
large and expanded. The pituitary body 
appears to have been large. 
The cervical vertebrae differ in type from 
those of any other known reptiles, being 
deeply concave behind, but flattened in 
front, leaving only a narrow margin for ¢”% 
articulation. Pelvis of Allosaurus fragilis Marsh; side view, seen from the left. a, acetabu- 
The bones of the pelvis, except the sa- lum; é/, ilium; és, ischium; p, pubis. 
crum, are all thoroughly co-ossified. The 
pelvis is extremely narrow, being in striking contrast like body, which probably served to support the ani- 
to the width in this region in the herbivorous mal when sitting down. 
