INTRODUCTION. IX 



with many species to which no generic position could be assigned. 

 If, in the course of time, advancing knowledge renders it advisable 

 to introduce a larger number of generic divisions, the present arrange- 

 ment will form a basis on which a more complicated superstructure 

 may be raised. 



The collection of the remains of Ichthyopterygia and Sauropterygia 

 preserved in the Museum is, as a whole, the finest in Europe, and 

 probably in the world : containing a large number of type speci- 

 mens. Through the courtesy of Prof. A. H. Green, of Oxford, Prof. 

 T. McKenny Hughes, of Cambridge, Mr. A. N. Leeds, of Eyebury 

 near Peterborough, and Dr. W. King, Director of the Geological 

 Survey of India, the Collection has been enriched during the progress 

 of the present work with casts of type and other important specimens 

 belonging to nearly all the English forms to which specific names 

 have been applied ; these casts having been moulded by the skilful 

 hands of Mr. C. Barlow, the Museum formatore. 



Leaving the subject of the present volume, it is necessary to draw 

 attention to certain erroneous determinations made in the previous 

 volume, and also to emendations in regard to some of the forms and 

 specimens therein mentioned. In some of these points the writer is 

 indebted to Prof. 0. C. Marsh, who visited the Museum during the 

 autumn of 1888. 



In the Ornithosauria the name Ptenodracon (p. 3) may be amended 

 to Ptenodraco. Passing to the Crocodilia, it has been found that the 

 genus Geosaurus (Pt. I. p. 271) is really a Crocodilian ; and since it 

 appears that Dacosaurus (p. 92) is not separable therefrom, Plien- 

 ingcr's name of Geosaurus maximus may be retained for the type of 

 the latter. Dermal scutes are absent both in this genus and Metrio- 

 rhynchus (p. 95), but sclerotic plates were present in the eye ; 

 which entails an amendment in the characters of the Crocodilia 

 given on p. 42. This also shows that the loricate Crocodilian men- 

 tioned on p. 98, to which the name Crocodiltemus has been applied, 

 is distinct from Metriorhynchus. iSee 'Quart. Journ. Geol. Soc.' 

 vol. xlv. pp. 5G-5S (1S8 ( J). 



In the Dinosauria the apparent resemblance of the vertebra? of 

 Bothrio&pondylus suffosus (p. 170) to the figure of the" vertebra of 

 Creosawus is not a real one ; and these specimens belong to an im- 

 mature Sauropod, or may perhaps indicate a smaller form allied to 

 tho American Pleurocalus, which may be the same as Cetiosaurus 



