736 S. W. WILLISTON 



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 LIST OF DESCRIBED NORTH AMERICAN PLESIOSAURS 



JURASSIC (bAPTANODON BEDS) 

 Plesiosaurus shirleyensis Knight. — Wyoming. 

 Pantosaarus striatus Marsh. — Wyoming. 

 Megalneusaurus rex Knight. — Wyoming. 

 CiinoUasaurus laraniiensis Knight. — Wyoming. 



LOWER CRETACeIAjS (cOMANCHE) 

 Plesiosaurus mudgei Cragin. — Kansas. 

 Plesiosaurus gouldi WilHston. — Kansas. 



BENTON CRETACEOUS 

 Trinacromerum bentonianum Cragin. — Upper, Kansas. 

 Trinacromerum anonymum Williston. — Upper, Kansas. , 

 Trinacromerum latimanus Williston. — Upper, Wyoming. 

 Brachauchenius lucasii Williston. — Middle or Lower, Kansas, Texas, 

 Elasmosaurus, n. sp. Williston. — Middle, Kansas. 



NIOBRARA CRETACEOUS 

 Elasmosaurus snowii Williston. — Middle, Kansas. 

 Elasmosaurus serpentinus Cope. — Nebraska, Wyoming. 

 Elasmosaurus marshii Williston. — Middle, Kansas. 

 Elasmosaurus ischiadicus Williston. — Upper, Kansas. 

 Elasmosaurus nobilis Williston. ^Basal, Kansas. 

 Elasmosaurus sternbergi Williston. — Middle, Kansas. 

 Polycotylus latipinnis Cope. — Kansas. 

 Polycotylus dolichopus Williston. — Kansas, Wyoming. 



FORT PIERRE CRETACEOUS 

 Plesiosaurus gulo Cope. — Kansas. 

 Elasmosaurus platyurus Cope. — Basal, Kansas. 

 Elasmosaurus intermedius Cope. — South Dakota. 

 Uronautes cetiformis Cope. — Montana. 

 Ophrosaurus pauciporus Cope. — Fox Hills, New Mexico. 

 Piptomerus megaloporus Cope. — Fox Hills, New Mexico. 

 Piptomerus microporus Cope. — Fox Hills, New Mexico. 

 Piptomerus hexagonus Cope. — Fox Hills, New Mexico. 

 Embaphias circulosus Cope. — South Dakota. 



CRETACEOUS OF NEW JERSEY AND THE SOUTH 

 Plesiosaurus brevifemur Cope. — Greensand No. 5, New Jersey. 

 Cimoliasaurus magnus Leidy. — Greensand No. 5, New Jersey. 

 Discosaurus planior Leidy. — Mississippi, New Jersey. 

 Brimosaurus grandis Leidy. — Arkansas. 

 Elasmosaurus orientalis Cope. — New Jersey. 

 Tapjirosaurus lockwoodi Cope. — No. i. New Jersey. 



OF DOUBTFUL RELATIONS AND HORIZON 

 Oligosimus primaevus Leidy. — Green River, Wyoming. 

 Piratosaurus plicatus Leidy. — Cretaceous. 



