﻿PREFACE. 



Finding that while there was much confusion as to the species of Cephalopoda, 

 especially of the Jurassic rocks, and at the same time much interesting material on 

 which good work had been done on the Continent, I entertained the desire of 

 undertaking a monograph of the group. Two grants from the Government Fund 

 in aid of Scientific Eesearch enabled me to devote the time to collecting the materials 

 from the various museums and private collections in the country ; but it soon 

 became evident that nothing short of a detailed description, with figures of the 

 various forms recognised, would be satisfactory : in fact, that I must aim at the 

 standard so admirably set by Mr. Davidson for the Brachiopoda ; and that though 

 I had collected all the materials for the Devonian and Carboniferous monograph, 

 the first part would have to be restricted to the Silurian, which, with the 

 Introduction, would make a fair-sized volume. This is now (still by the aid of the 

 Government grant) presented to the public, and I hope to be able shortly to 

 produce Part II., which will include the rest of the Palaeozoic forms. 



It might seem natural that this work should be published by the Palgeonto- 

 graphical Society, but I have not asked their acceptance of it — partly because it is 

 well known that they have much more material already offered than their yearly 

 volume can find room for, and any independent work thus renders the day nearer 

 when our British Fossils will be adequately described ; and partly because, with the 

 aid I have received from the Government Research Fund, it seems to me only right 

 to test, at least, the demand for such works beyond what is satisfied by the fixed 

 annual amount published by the Palasontographical Society. Still, as the work is 

 strictly of the same kind as that published by the Society, I have made the form 

 and style of printing as nearly as possible similar to their publications. 



Whether the original design, which led to the present undertaking, of clearing 

 up the history of the Jurassic Cephalopoda, will ever be realised, depends on future 

 circumstances, of which I have no prescience. 



The. method pursued in working up the present part has been as follows : — I 

 first collected into one book, arranged under the names used by the authors, copies 

 of all the figures given of any British Silurian Cephalopod, or shell supposed to 



