CONTENTS. 
Preface ‘ : : ; : - : : ‘ 3 ; 
Memoir on the Extinct Reptiles of the Cretaceous Formations of the United States 
Introduction 
Sanria 
Thoracosaurus heocesariensis 
Bottosaurus Harlani 
Undetermined Species of Crocodiles . 
Hyposaurus Rogersii 
Discosaurus vetustus 
Cimoliasaurus magnus 
Piratosaurus plicatus 
Mosasaurus 
Macrosaurus levis 
Polygonodon vetus . 
Hadrosaurus Foulkii F ; 
Undetermined Reptiles allied to Hadrosaurus 
Astrodon Johnstoni 
Tomodon horrificus . 
Pliogonodon priscus 
Chelonia 
Chelone sopita 
Chelone ornata 
Emys firmus 
Emys beatus 
Emys prayus 
Platemys sulcatus 
Bothremys Cookii 
Trionyx priscus 
A Synopsis, in which an attempt is made to define more closely the Genera and Species whose 
remains are described in the preceding pages 
Index ; ; 
References to the Plates . 
