Prof. 0. C. Marsh — Classification of Dinosaurs. 



395 



Genera Cardiodon (Cetiosauras), Bothriospondylus, Omithopsis, 

 and Pelorosaurus. European, and probably all Jurassic. 1 

 Order Predentata. Herbivorous. 



Narial opening lateral ; no antorbital foramen ; brain case ossified ; 

 supra-orbital bones ; teeth with sculptured crowns ; maxillary teeth 

 with crowns grooved on outside ; lower teeth with grooves on inside 

 of crown ; a predentary bone ; dentary with coronoid process. Cer- 

 vical ribs articulating with vertebrae ; each sacral rib supported by 

 two vertebras. Ilium elongated in front of acetabulum ; prepubio 

 bones free in front ; postpubic bones present ; ischia slender, directed 

 backward, with distal ends meeting side to side. Astragalus without 

 ascending process. 



Sub-order Stegosaukia (Plated lizard). 



Skull without horns ; no teeth in premaxillaries ; teeth with dis- 

 tinct compressed crowns and serrated edges. Fore limbs small. 



Fig. 5. — Stegosaurus ungulatos, Marsh. - 6 V Jurassic, Wyoming. 

 Vertebra? and limb bones solid. Pubes projecting free in front ; 

 postpubis present. Femur longer than tibia; feet plantigrade, 

 ungulate ; five digits in manus and four in pes ; second row of carpals 

 and tarsals unossified ; locomotion mainly quadrupedal. Osseous 

 dermal armour. 



(1) Family Steyomurida. Vertebras biconcave. Neural canal in 

 sacrum expanded into large chamber ; ischia directed backward, with 

 sides meeting on median line. Dorsal ribs T-shaped in cross section. 

 Astragalus coossified with tibia; metapodials very short; five digits 

 in manus ; tbree functional digits in pes. Back surmounted by 

 a crest of vertical plates ; tail armed with one or more pairs of large 

 spines. (Figure 5.) 



1 The "Wealden is here regarded as Upper Jurassic, and not Cretaceous. See 

 0. C. Marsh, Geol. Mag., Decade IV, Vol. Ill, 1896, p. 8 ; and A. S. Woodward, 

 pp. 69-71, " On the Affinities of the "NVealdeu Fauna and Flora." 



