Prof. 0. C. Marsh — Classification of Dinosaurs. 391 



or hollow. Pubes slender, with anterior margins united ; an inter- 

 pubic bone. Femur longer than tibia; astragalus with ascending 

 process. 



Genus Labrosaurus. Jurassic, North America. 



(4) Family Plateosanrida (Zanclodontidce). Vertebrae biconcave ; 

 two sacral vertebras. Ilium expanded behind acetabulum ; pubes 

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

 bone ; ischia expanded at distal ends. Femur longer than tibia ; 

 astragalus without ascending process. Five digits in manus and 

 pes. 



Genera Plateosaurus (Zanclodon), ? Teratosaurus, Bimodosaurus. 

 Triassic. Known forms European. 



(5) Family Anchisauridce. Skull light in structure, with re- 

 curved cutting teeth. Vertebras biconcave. Bones hollow. Ilium 

 expanded behind acetabulum ; pubes rod-like and not coossified 

 distally ; no interpubic bone. Fore limbs well developed ; femur 

 longer than tibia; astragalus without ascending process; five digits 

 in manus and four in pes. (Figure 1.) 



Fig. 1. — Anchisatjiujs colurus, Marsh. ■£$. Triassic, Connecticut. 

 Genera Anchisaurus (Megadactylus), Ammosaurus, ? Arctosaurus, 

 Bathygnathus, and Clepsysanrus, in North America ; and in Europe, 

 Palceosaurus, Thecodontosaurus. All known forms Triassic. 



Sub-order Cceluria (Hollow tail). 



(6) Family Cceluridce. Teeth much compressed. Vertebras and 

 bones of skeleton very hollow or pneumatic ; neural canal much 

 expanded ; anterior cervical vertebras convexo-concave ; remaining 

 vertebras biconcave ; cervical ribs coossified with vertebras. An 

 interpubic bone. Femur shorter than tibia ; metatarsals very long 

 and slender. 



Genera Coelurus, in North America ; and Aristosuchus, in Europe 

 Jurassic. 



