764 



HISTORICAL GEOLOGY. 



1213. 



Marsh, the corresponding dimensions of a cervical vertebra (Fig. 1213) being 

 4 feet and 2-|- feet. In Atlantosaurus immanis Marsh, a species probably 70 

 or 80 feet long, the femur was over six feet in length. 



(&) Stegoscmrians. The Stegosaurs of Marsh were other huge species, but 



with the fore limbs much the shorter, and 

 all the bones solid. They were remarkable 

 for the crest of great bony plates along the 

 back, the diminutive size of the brain, and 

 the enormous supplementary nervous mass 

 in the sacrum. The figure is the restora- 

 tion of Stegosaurus tingulatus Marsh, by the 

 describer, -^ the natural size. The head 

 had a horny beak. The throat was covered 

 with small ossicles. The larger of the 

 plates along the back were li feet broad ; 

 and the spines along the caudal portion, 

 nearly 2 feet long. All the plates and 

 spines had originally a thick horny cover- 

 ing. The relative size of the brain and the nervous mass in the sacrum is 

 shown in the figures, of ^ natural size : Fig. 1215, the brain ; 1216, the mass 

 in the sacrum. 



Fig. 1213, Apatosaurus laticollis, cervical 

 vertebra (,Xj>g1; c, concave posterior 

 articular surface ; d, diapophysis ; p, para- 

 popysis ; h, hatchet bone, or anchylosed 

 rib ; z', postzygapophysis. Marsh. 



1214. 



1214 a. 



Fig. 1214, restoration of Stegosaurus ungulatus (x s'o) ; 1214 a, tooth of same (x 2). Marsh. 



(c) Ornithopoda. — The animals of this group of Herbivorous Dinosaurs 

 were bird-like in feet, and strikingly so in the pelvic bones. Both of these 

 characters are shown in the restoration of Camptosaurus dispar of Marsh 



