0. C. Marsh— Classification of the Dinosauria. 83 
Regarding the Dinosaurs as a sub-class of the REPTILiA, the 
forms best known at present may be classified as follows: 
Sup-Cuiass DINOSAURIA. 
Premaxillary bones separate; upper and lower temporal 
arches; ramiof lower jaw united in front by cartilage only; no 
teeth on palate. Neural arches of vertebree united to centra by 
suture; cervical vertebree numerous; sacral vertebree codssi- 
fied. Cervical ribs united to vertebrae by suture or ankylosis ; 
thoracic ribs double-headed. Pelvic bones separate from each 
other, and from sacrum; ilium prolonged in front of acetabu- 
(1.) Order Savropopa (Lizard foot.) Herbivorous. 
Feet plantigrade, ungulate; five digits in manus and pes; 
second row of carpals and tarsals unossified. Pubes project- 
Precaudal vertebree hollow. Fore and hind limbs nearly 
equal; limb bones solid. Sternal bones parial. Premaxillaries 
with teeth. 
_(L) Family Adlantosauride. Anterior vertebrae opisthocce- 
lian. Ischia directed downward, with extremities meeting on 
median line. 
Genera Atlantosaurus, Apatosaurus, Brontosaurus, Diplodocus, 
? Camarasaurus (Amphicelias), ? Dystropheus 
2.) Family Morosauride. Anterior vertebre opisthoccelian. 
Ischia directed backward, with sides meeting on median line, 
Genus Morosaurus. 
uropean forms of this order: Bothriospondylus, Cetiosaurus, 
Chondrosteosaurus, Eucamerotus, Ornithopsis, Pelorosaurus. 
(2.) Order Srrgosaurta (Plated lizard). Herbivorous. 
Feet plantigrade, ungulate; five digits in manus and pes; 
second row of carpals unossified. ubes projecting free in 
front ; post-pubis present. Fore limbs very small; locomotion 
mainly on hindlimbs. Vertebre and limb bones solid. Osseous 
dermal armor. 
_ (1) Family Stegosauride. Vertebree biconcave. Neural canal 
in sacrum expanded into large chamber; ischia directed back- 
ward, with sides meeting on median line. Astragalus codssi- 
fied with tibia; metapodials very short. 
» 
