PREFACE. 



During the past twenty years the British Museum has gradually acquired the fine 

 collection of Eeptilian skeletons obtained by the Messrs. Leeds, of Eyebury, from the 

 Oxford Clay in the neighbourhood of Peterborough. Most of the specimens represent 

 marine Reptiles of the Orders Ichthyopterygia, Sauropterygia, and Crocodilia; and 

 the associated sets of bones have been extricated from the rock with so much skill 

 and care that they aiford an unique opportunity for acquiring a good general 

 knowledge of the Reptilian fauna existing in the Upper Jurassic sea. Dr. Charles 

 W. Andrews has therefore been entrusted with the preparation of a Descriptive 

 Catalogue of the collection, and it is hoped that his exhaustive work will form a 

 iiseful basis for future researches in the same field. The separate bones of many of 

 these reptiles have now been studied and described as thoroughly and satisfactorily as 

 if they were from freshly-macerated skeletons ; and it is only to be regretted that a 

 considerable proportion of the specimens are too much distorted by crushing in the 

 soft moist clay to allow of any exact measurements. The variations observed in the 

 difi^erent individuals of some species are especially noteworthy ; and the growth-stages 

 traceable in certain parts, such as the Elasmosauriau shoulder-girdle, are also of great 

 interest. In accomplishing his task Dr. Andrews has been much assisted by Mr. Alfred 

 N. Leeds, who made the greater part of the collection, and has given the Museum the 

 benefit of his long experience. 



Part I. contains the account of the Ichthyosaurs and Plesiosaurs. 

 will be devoted to the Pliosaurs and Crocodiles. 



Part IL 



A. SMITH WOODSY ARD. 



Depaetment of Geologt, 



Beitish Museum (Natueal Histohy), 



ISth Julv, 1910. 



a2 



