294 THE OSTEOLOGY OF THE REPTILES 



Hulke, Nesodon Mousaye, Oplosaurus Gervais, Ornithopsis Seeley, 

 Europe. 



Lower Cretaceous (Morrison). Barosaurus Marsh/ Caulodon 

 Cope,2 Elosaurus Peterson and Gilmore, Epanterias Cope, Symphy- 

 rophus Cope, ? Astrodon Leidy, Rocky Mts. 



Lower Cretaceous. Dinodocus Owen, Hypselosaurus Matheron, 

 Aepysaurus Gervais, Morinosaurus Sauvage, Europe. 



Algaosaurus Broom, South Africa. 



Upper Cretaceous. Argyrosaurus Lydekker, Microcoelus Lydek- 

 ker, South America. 



18. ORDER ORNITHISCHIA 

 [Orthopoda, Predentata] 

 Quadrupedal or bipedal dinosaurs, especially characterized by the 

 presence of a predentary bone in the mandible and by the structure of 

 the pelvis. Premaxillae rarely with teeth. Antorbital openings small 

 or absent. Vertebrae amphicoelous or amphiplatyan, the anterior 

 ones often opisthocoelous. Pubes not meeting in a median symphy- 

 sis, with an anterior, more or less spatulate, prepuhis, and a posterior, 

 usually long, postpuhis, underlying the ischium. Front limbs always 

 shorter than hind, never functionally pentadactylate, rarely with as 

 many as four phalanges in any digit. Hind Umbs usually function- 

 ally tridactylate, more or less digitigrade. Ungual phalanges short 



and broad. 



A. Suborder Ornithopoda 



Bipedal in habit, digitigrade. External nares near extremity of 

 face, divided. Postpubis complete, slender. Antorbital opening 

 sometimes small. 



Family Nanosauridae. Premaxillae edentulous. Teeth in a 

 single row, compressed and pointed. Vertebrae amphicoelous; three 

 sacrals. Femur shorter than tibia. Bones very hollow. Of the size 

 of a cat. 



Lower Jurassic. Nanosaurus Marsh, Colorado. 



Family Hypsilophodontidae. Premaxillae with teeth. Teeth in 

 a single row. Anterior vertebrae opisthocoelous. Femur longer than 



1 [Belongs in the Diplodocidae. — Lull.] 



2 [Belongs in the Camarasauridae. — Osborn and Mook.] 



