496 0. C. Marsh—On Dinosaurian Reptiles. 
(4) Family Pleurocelide. Dentition weak; teeth resem- 
bling those of Dzplodocus. Cervical vertebrae elongated ; cen- 
trum hollow, with large lateral openings; sacral vertebre solid, 
with lateral depressions in centra; caudal vertebre solid ; ante- 
rior caudals with flat articular faces, and transversely compressed 
neural spines; middle caudal vertebree with neural arch on front 
half of centrum. Ischia with compressed distal ends, meeting 
on median line. 
Genus Pleurocelus. % Jurassic, North America. 
(5) Family Z2tanosauride. Fore limbs elongate; coracoid 
quadrilateral. Presacral vertebreze opisthoccelian ; first caudal 
vertebra biconvex; remaining caudals proceelian ; chevrons open 
above. 
Genera TZitanosaurus and Argyrosaurus.  % Cretaceous, 
India and Patagonia. 
European forms of the order Sauropoda are Bothriospondy- 
lus, Cardiodon (Cetiosaurus), Chondrosteosaurus, Hucamero- 
tus, Ornithopsis, and Pelorosaurus. All probably Jurassic.* 
Order PREDENTATA. MHerbivorous. 
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. Cervical ribs articulating with verte- 
bre; each sacral rib supported by two vertebrae. Ilium elon- 
gated in front of acetabulum; prepubic bones free in front; 
postpubic bones present; ischia slender, directed backward, 
with distal ends meeting side to side. Astragalus without 
ascending process. 
Suborder STEGOSAURIA (Plated lizard). 
No teeth in premaxillaries; teeth with distinct compressed 
crowns, and serrated edges. Fore limbs small; locomotion 
mainly quadrupedal. Vertebree and limb bones solid. Pubes 
projecting free in front ; postpubis present. Iemur longer than 
tibia. Feet plantigrade, ungulate ; five digits in manus and four 
in pes; second row of carpals unossified. Osseous dermal armor. 
(1) Family Stegosauride. Vertebre 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 codssified with tibia; 
metapodials very short. Five digits in manus; three fune- 
tional digits in pes. (Plate X, figure 8.) 
* The Wealden is here regarded as upper Jurassic, and not Cretaceous. See 
this Journal, vol. 1, p. 412, November, 1895. 
