i8o EXTINCT MONSTERS 
a somewhat different representation of the Stegosaur, in which 
the length of the hind limbs is more apparent, and also they are 
more free from the body. 
Finally, the Stegosaur displays a rather remarkable feature; 
for a very large chamber was found in the sacrum ^ formed by 
Fig. 64. — 1, 2. Plates of Stegosaurus. The middle figures show their thickness. 
(After Marsh.) 
an enlargement of the spinal cord. 
The next monster to be described is one that has fortunately 
left to posterity a good record of itself, and probably was 
not very unlike the Hylseosaurus of Mantell. This is the 
^ The sacrum may be thus defined : the Vertebrae (usually fused together) 
which unite with the haunch-bones (ilia) to form the pelvis. 
