Dinosauria — Theropoda. 
13 
Sub-order 2. — Theropoda (Beast-footed). 
The Theropoda hold an intermediate position between the ^ o al ;i,' case ’ 
Sanropoda and the Omithopoda, although more nearly allied °' 
to the former. In the structure of the teeth, the form of the 
femur ; the occasional presence of only two sacral vertebrae, 
and in the form of the quadrate bone, certain genera approach 
more nearly to the Crocodilia than even do the Sauropoda ; 
although in their hollow limb-bones they agree with the 
Fig. 15 .— Left side of pelvis of Allosaurus fragilis (Marsh), from the Upper Jurassic 
of North America (Jj nat. size), a, acetabulum; il, ilium; p, pubis; is, ischium 
(after Marsh). 
Ornithopoda. All the forms were carnivorous. The premax- 
illary was furnished throughout with teeth, which are laterally 
compressed and backwardly curved, the cutting edges of one or 
both of which are frequently serrated. The teeth are planted 
in distinct sockets, and the skull has a large aperture in front of 
the eye, known as the preorbital vacuity. The centra of all the 
vertebra are hollowed internally, and much compressed laterally. 
