O. C. Marsh—On Dinosaurian Reptiles. 495 
Order SaAuRoPopDA (Lizard foot). Herbivorous. 
External nares at apex of skull; premaxillary bones with 
teeth; teeth with rugose crowns more or less spoon-shaped ; 
large antorbital openings; no pineal foramen; alisphenoid 
bones ; brain case ossified ; no columellee ; postoccipital bones ; 
no predentary bone; dentary without coronoid process. 
Cervical ribs codéssified with vertebrae; anterior vertebra 
opisthoccelian, with neural spines bifid; posterior trunk verte- 
bree united by diplosphenal articulation ; presacral vertebrae 
hollow; each sacral vertebra supports its own transverse 
process, or sacral rib; no diapophyses on sacral vertebre ; 
neural cavity much expanded.in sacrum. Sternal bones parial. 
Ilinm expanded in front of acetabulum; pubes projecting in 
front, and united distally by cartilage; no postpubis. Limb 
bones solid; fore and hind limbs nearly equal; metacarpals 
longer than metatarsals; femur longer than tibia; feet planti- 
grade, ungulate; five digits in manus and pes; second row of 
carpal and tarsal bones unossified. Locomotion quadrupedal. 
(1) Family Adlantosauride. A pituitary canal; large fossa 
for nasal gland. Distal end of scapula not expanded. Sacrum 
hollow; ischia directed downward, with expanded extremities 
meeting on median line. Anterior caudal vertebre with 
lateral cavities; remaining caudals solid. 
_ Genera Atlantosaurus, Apatosaurus, Barosaurus, Bronto- 
saurus. Include the largest known land animals. Jurassic, 
North America. (Plate X, figure 2.) 
(2) Family D¢éplodocide. External nares superior; no 
depression for nasal gland; two antorbital openings; large 
pituitary fossa; dentition weak, and in front of jaws only; 
brain inclined backward; dentary bone narrow in front. 
Ischia with shaft not expanded distally, directed downward 
and backward, with sides meeting on median line. Sacrum 
hollow. Caudal vertebree deeply excavated below ; chevrons 
with both anterior and posterior branches. 
Genus Diplodocus. Jurassic, North America. 
(8) Family Morosauride. External nares lateral; large 
fossa for nasal gland; small pituitary fossa; dentary bone 
massive in front. Shaft of scapula expanded at distal end. 
Sacral vertebre nearly solid; ischia slender, with twisted shaft 
directed backward, and sides meeting on median line. Ante- 
rior caudals solid. 
Genera Morosaurus, ?Camarasaurus (Amphicelias). 
Jurassic, North America. 
