Prof. 0. C. Marsh 07i the Dinosauria. 81 



ossified. Cervical ribs united to vertebrte by suture or anky- 

 losis ; thoracic ribs double-headed. Pelvic bones separated 

 from each other and from sacrum ; ilium prolonged in front 

 of acetabulum 5 acetabulum formed in part by pubis ; ischia 

 meet distally on median line. Fore and hind limbs present, 

 the latter ambulatory and larger than those in front ; head of 

 femur at right angles to condyles ; tibia with procnemial crest ; 

 fibula complete. First row of tarsals composed of astragalus 

 and calcaneum only, which together form the upper portion 

 of ankle-joint. 



(1.) Order Saueopoda (Lizard-foot). Herbivorous. 



Feet plantigrade, ungulate ; five digits in manus and pes ; 

 second row of carpals and tarsals unossified. Pubes pro- 

 jecting in front, and united distally by cartilage ; no post- 

 pubis. Precaudal vertebras hollow. Fore and hind limbs 

 nearly equal ; limb-bones solid. Sternal bones parial. Pre- 

 maxillaries with teeth. 



(1.) Family Atlantosauridce. Anterior vertebra^, opistho- 

 coelian. Ischia directed downward, with extremities meeting 

 on median line. 



Genera : Atlantosaurus ^ Apatoscmrus, BronfosauruSj Dijjlo- 

 docus, ? Camarasaurus (Amjihica'Iias), ? DT/strojy/iceus. 



(2.) Family Morosauridcv. Anterior vertebras opistho- 

 coelian. Ischia directed backward, with sides meeting on 

 median line. 



Genus Morosaurus. 



European forms of this order : Botlmospondylus^ Ceteo- 

 sauriiSj ChondrosfeosauruSj EacavierotuSj Omithopsis, Pcloro- 

 saurus. 



(2.) Order Stegosauria (Plated lizard). Herbivorous. 



Feet plantigrade, ungulate ; five digits in manus and pes ; 

 second row of carpals unossified. Pubes projecting free in 

 front ; postpubis present. Fore limbs very small j locomotion 

 mainly on hind limbs. Vertebras and limb-bones solid. Osse- 

 ous dermal armour. 



(1.) Family Stegosauridce. Vertebras biconcave. Neural 

 canal in sacrum expanded into large chamber; ischia directed 

 backward, with sides meeting on median line. Astragalus 

 coossified with tibia ; metapodials very short. 



Genera: Stegosaurus {ilypsirliophus) ^ Diracodon^ and in 

 Europe Omosaurus^ Owen. 



(2.) Family Scelidosauridce. Astragalus not coossified 

 with tibia ; metatarsals elongated ; four functional digits in 

 pes. Known forms all European. 



