500 



GEOLOGY OF THE DENVER BASIN. 



cavity. Figs. 54 and 55 show the comparative size of the brain cavity 

 and the chamber in the sacrum. The physiological effects of a posterior 

 nervous center so many times larger than the brain itself is a suggestive 

 subject which need not here be discussed. It is evident, however, that in 

 an animal so endowed the posterior part was dominant. 



The dermal armor of Stegosaurus is one of its most remarkable features, 

 and suggested the generic name. A plate and spine are shown in fi^'s. 56 

 and 57, and the series are in place in the restoration, PI. XXII. 



In the restoration of Stegosaurus given on PI. XXII, the animal is 

 represented as walking, and the position is adapted to that motion. The 



in, 56 Dermal spino of Stetwaaurtis ungulatus. 

 ». side view; b, front view; r section: d, inferior 



I'n.. 57.*— Dermal plate of St< wsa ungulatua 



a, side view; &, end view of base ; d, tliin margin; 

 Both figures are one-twelfth Datura] size 



ikiil by vascular <;rooves. 



head and neck, the massive fore limbs, and, in fact, the whole skeleton, 

 indicate slow locomotion on all four feet. The longer hind limbs and the 

 powerful tail show, however, that the animal could thus support itself, as 

 on a tripod, and tins position could have been very easily assumed in 

 consequence of the massive hind quarters. 



In the restoration as here presented the dermal armor is the most 

 striking feature, but the skeleton is almost as remarkable, and its high 

 specialization was evidently acquired gradually as the armor itself was 

 developed. Without the latter many points in the skeleton would be 

 inexplicable, and there are still a number that need explanation. 



