Three species of Pterotrigonia from Cretaceous rocks of the W. coast of North America, P. evansana (Meek), P. klamathonia (Anderson), and P. oregana (Packard), are redescribed and figured. Trigonia inezana Packard and T. churchi Anderson are considered to be synonyms of P. evansana, T. deschutesensis Packard is considered to a synonym of P. oregana. P. evansana ranges from the Coniacian to the Campanian; P. klamathonia ranges throughout the Turonian, and P. oregana ranges from lower to middle Albian to about upper Cenomanian.

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