THE SUBCLASS DIAPSIDA 293 



twenty-seven presacrals. The pubes are massive and meet in a large 

 ventral symphysis. Carpals and tarsals reduced, feet preaxial. Limb 

 bones cancellous in structure. From about fifteen to about ninety 

 feet in length. 



Family Cetiosauridae. Spines of dorsal vertebrae simple, not 

 furcate. Front limbs as long as the hind. Scapulae dilated distally. 

 Pubes not constricted. 



Upper Jurassic. Cetiosaurus Owen {Cardiodon Owen), England. 



Lower Cretaceous (Morrison). Haplacanthosaurus Hatcher, Bra- 

 chiosaurus Riggs, Rocky Mts. Gigantosaurus Fraas (non Seeley), 

 {} Brachiosaurus Riggs), South Africa. Pelorosaurus Man tell, 

 Europe, Madagascar. 



Family Camarasauridae. Spines of dorsal vertebrae furcate. 

 Front hmbs distinctly shorter than hind. Scapulae distally ex- 

 panded. Ischia slender. 



Lower Cretaceous. Camarasauriis Cope {Morosaurus Marsh), 

 Pleurocoelus Marsh, North America. Titanosaurus Lydekker, 

 Europe, Madagascar, India. 



Upper Cretaceous. Titanosaurus Lydekker, France, Patagonia. 



Family Atlantosauridae. Spines of presacral vertebrae furcate. 

 Front legs much shorter than hind. Scapulae narrow distally. 

 Ischia expanded at extremity. 



Lower Cretaceous (Morrison). Atlantosaurus Marsh, Apatosaurus 

 Marsh (Brontosaurus Marsh), Amphicoelias Cope, Rocky Mts.^ 



Family Diplodocidae. Spines of presacral vertebrae furcate. 

 Front legs shorter than hind. Teeth slender, confined to anterior 

 part of jaws. External nares near top of skull, remote from extrem- 

 ity. Ischia not expanded distally, the pubes constricted in middle. 

 More slender sauropods. 



Lower Cretaceous (Morrison). Diplodocus Marsh, Rocky Mts. 



Genera Incertae Sedis: ? Jurassic. Dystrophaeus Cope, Rocky 

 Mts. 



Upper Jura and Wealden. Bothriospondylus Mantell, Chondrosteus 

 Owen, Chondrosteosaurus Owen, Eucamerotus Hulke, Ischyrosaurus 



^ [Belongs in Diplodocidae. — Osborn and Mook.] 



