494 - O. C. Marsh—On Dinosaurian Reptiles. 
Suborder Ca@LurtA (Hollow tail). 
(6) Family Caluride. Teeth much compressed. Verte- 
bree and bones of skeleton very hollow or pneumatic; anterior 
cervical vertebree convexo-concave;. remaining vertebre 
biconcave; cervical ribs codssified with vertebree; an inter- 
pubic bone. Femur shorter than tibia. Metatarsals very long 
and slender. 
Genera Celurus, in North America; and Avristosuchus, in 
Europe. Jurassic. 
Suborder CoMPSOGNATHA. 
(7) Family Compsognathide. Skull elongate, with slender 
jaws and pointed teeth. Cervical vertebree convexo-concave ; 
remaining vertebre biconcave. Bones very hollow. Femur 
shorter than tibia. Ischia with long symphysis on median 
line. Three functional digits in manus and pes. 
Genus Compsognathus. Jurassic. Only known specimen 
European. (Plate X, figure 3.) 
Suborder CERATOSAURIA (Horned saurians). 
(8) Family Ceratosauridew. Horn on skull. Cervical verte- 
bree plano-concave; remaining vertebre biconcave. Pelvic 
bones coéssified; ilium expanded in front of acetabulum ; 
pubes slender; an interpubic bone. Limb bones hollow. 
Manus with four digits. Jemur longer than tibia; astragalus 
with ascending process; metatarsals codssified; three digits 
only in pes. Osseous dermal plates. (Plate X, figure 5.) 
Genus Ceratosaurus. Jurassic, North America. 
(9) Family Ornithomimide. Pelvic bones codssified with 
each other and with sacrum; ilium expanded in front of acetab- 
ulum. Limb bones very hollow. Fore limbs very small ; 
digits with very long, pointed claws. Hind limbs of true 
avian type; feet digitigrade and unguiculate. 
Genus Ornithomimus. Cretaceous, North America. 
Suborder HALLOPODA (Leaping foot). 
(10) Family Haliopide. Vertebree and limb bones hollow ; 
vertebree biconcave; two vertebre in sacrum; acetabulum 
formed by ilium, pubis, and ischium; pubes rod-like, project- 
ing downward, but not codssified distally; no postpubis ; 
ischia with distal ends expanded, meeting below on median 
line. Fore limbs very small, with four digits in manus. 
Femur shorter than tibia; hind limbs very long, with three 
digits only in pes, and metatarsals greatly elongated; astragalus 
without ascending process; caleaneum much produced back- 
ward ; feet digitigrade, unguiculate. 
Genus Hallopus. Jurassic, North America. 
