INTRODUCTION. 



I DELAYED the Index to my Monograpli an the Oolitic Echinoidea in the 

 hope that after the publication of the Fourth Part some new species from time to 

 time would be discovered in our Jurassic rocks, and thereby have necessitated a 

 Supplement to the work. Up to the present time I have waited for new forms in 

 vain ; and, as numerous inquiries have been made for the index, my most kind and 

 considerate friend, our worthy Secretary, knowing how much my time is occupied 

 with important public duties, kindly offered to prepare the same, and the members 

 of the Palaeontographical Society owe to the Rev. Thomas Wiltshire, M.A., 

 Sec. Gr.S., their thanks for the full and well- classified Index which accompanies 

 this sheet. 



In taking a retrospective glance at the progress of the Monograph it is very 

 satisfactory to find that so little remains to be added to the Oolitic species of 

 Echinoidea described and figured therein ; and indeed, as far as I am aware, 

 nothing requires to be retracted from any of its pages. It has been my constant 

 endeavour throughout the many years I have been engaged in its composition to 

 do ample justice to all naturalists who, either as contemporaries or as predecessors, 

 have been engaged in the study of the interesting groups of fossil forms included 

 in the class Echinodermata. 



Since I commenced this Oolitic Monograph several very important works have 

 enriched this branch of Palgeontology. In France my learned friend M. Gustave 

 Cotteau has published ' jfitudes sur les Echinides fossiles du Departement de 

 I'Yonne.' The first volume contains figures and descriptions of all the species 

 in the Terrain Jurassique, and the second volume is dedicated to the Cretaceous 

 species, which I shall notice in due course in my Memoir on the Echinoids from 



