PREFACE. 



In the earlier part of this Catalogue Mr. Lydekker was enabled to 

 include the Pterodactyles, the Crocodiles, the Dinosaurs, the Lizards 

 and Snakes, the Rhynchocephalia, and the Proterosauria. The 

 present volume, although of equal size, contains only the so-called 

 Enaliosaurians, comprising two divisions of mostly marine reptiles 

 — the Ichthyo pterygia and the Sattropterygia, of which the 

 most important genera, Ichthyosaurus and Plesiosaurus, are repre- 

 sented by a series of specimens that are probably unrivalled in any 

 other Museum in the world. 



But little difficulty has been experienced in dealing with the 

 species of the first order, which, with two exceptions, happily 

 remain all included in the genus Ichthyosaurus (the exception 

 being in the case of two species referred to the genus Ophthalmo- 

 saurus of Prof. Seeley). 



The second Order (Sauropterygia) has necessarily been subdivided 

 into four families and into quite a number of genera, as : — Pliosaurus, 

 Peloneustes, Thaumatosaurus, Polyptychodon, Cimoliosaurus, Eret- 

 mosaurus, and Plesiosaurus, forming the Plesiosauridae ; Lariosaurus 

 and Neusticosaurus — the Lariosaurida3 ; Pistosaurus, Nothosaurus 

 and Conchiosaurus — the Nothosauridie ; and Mesosaurus the Meso- 

 sauriduc. 



