marsh.] THEROPODA. 239 



Order Theropoda (Beast foot). Carnivorous. 



Skull with external narial openings lateral; large antorbital vacuity; 

 brain case incompletely ossified ; no pineal foramen ; premaxillari.es with 

 teeth; no predentary bone; deutary without coronoid process; teeth 

 with smooth compressed crowns and crenulated edges. Vertebra; more 

 or less cavernous; posterior trunk vertebrae united by diplosphenal 

 articulation. Neural canal in sacrum of moderate, size. Each sacral rib 

 supported by two vertebrae ; diapophyses distinct from sacral ribs. Ster- 

 num unossified. Pubes projecting downward, and united distally; no 

 postpubis. Fore limbs small; limb bones hollow; astragalus closely 

 applied to tibia ; feet digitigrade; digits with prehensile claws; locomo- 

 tion mainly bipedal. 



(1) Family Megalosaurida?. Lower jaws with teeth in front. Anterior 

 vertebra? convexo-concave; remaining vertebra; biconcave; five sacral 

 vertebra?. Abdominal ribs. Ilium expanded in front of acetabulum; 

 pubes slender, and distally coossified. Femur longer than tibia; astrag- 

 alus with ascending process; five digits in manus and four in pes. 



Genus JMegalosaurus (Poikilopleuron). Jurassic and Cretaceous. 

 Known forms, European. 



(2) Family Dryptosauridre. Lower jaws with teeth in front. Cervi- 

 cal vertebra? opisthocoelian ; remaining vertebra? biconcave; sacral ver- 

 tebra? less than five. Ilium expanded in front of acetabulum ; distal ends 

 of pubes coossified and much expanded; an interpubic bone. Femur 

 longer than tibia; astragalus with ascending process; fore limbs very 

 small, with compressed prehensile claws. (Pis. X-XII.) 



Genera Dryptosaurus (La?laps), Allosaurus, Ccelosaurus, Creosaurus. 

 Jurassic and Cretaceous. All from North America. 



(3) Family Labrosaurida?. Lower jaws edentulous in front. Cervi- 

 cal and dorsal vertebra? convexo-concave; centra cavernous or hollow. 

 Pubes robust, with anterior margins united ; an interpubic bone. Femur 

 longer than tibia; astragalus with ascending process. (PI. XIII.) 



Genus Labrosaurus. Jurassic, North America. 



(4) Family Plateosaurida? (Zanclodontida?). Vertebra? biconcave; 

 two sacral vertebra?. Ilium expanded behind acetabulum; pubes 

 broad, elongate plates, with anterior margins united; no interpubic 

 bone; ischia united at distal ends. Femur longer than tibia; astrag- 

 alus without ascending process; five digits in manus and pes. 



Genera Plateosaurus (Zanclodon), Teratosaurus (!), Diniodosaurus. 

 Triassic. Known forms, European. 



(5) Family Anchisaurida?. Skull light in structure, with recurved, 

 cutting teeth. Vertebra? plane or biconcave. Bones hollow. Ilium 

 expanded behind acetabulum; pubes rod-like and not coossified dis- 

 tally; no interpubic bone. Fore limbs well developed; femur longer 

 than tibia; astragalus without ascending process; five digits in manus 

 and in pes. (Pis. II-IV.) 



Genera Anchisaurus (Megadactylus), Ammosaurus, Arctosaurus (?), 



