6 Index to Desors Sy7iopsis. 



they also contain some species and names that do not occur in the body of 

 the work. Many names that occur only in these places, or in the additions and 

 small-type notes of the Synopsis, are likely to be overlooked, and it is difficult to 

 find them without such an Index as the present. Not only is every page 

 referred to, but when there were two or more issues of a page, each is entered 

 and distinguished by the addition of the date, thus (1857). 



This last point is of particular importance, for, although every bound copy 

 of the Synopsis is furnished with a title-page bearing the imprint " Paris, 

 Wiesbade, 1858," and although the book is always assigned to that year in 

 Library Catalogues and Bibliographies, still it was really published in livraisons 

 or fascicules issued at various dates from 1855 to 1858; and some of the pages 

 in earlier fascicules were subsequently cancelled and replaced by fresh pages, 

 sometimes of increased number. Some names, e.g. Palaeocidaris, occur only in 

 the earlier issues ; others, e.g. Leiocidaris, only in the later ones. 



To the systematist a knowledge of the dates at which the various fascicules 

 were issued, and of the changes made in the text of cancelled pages, is an 

 undoubted necessity ; but it is a knowledge that most of us have been quite 

 unable to obtain. It is therefore a peculiar pleasure to me to be able to publish 

 with this Index a Bibliographic Note from the pen of Mr. Jules Lambert, whose 

 profound knowledge of the fossil echinoids and of the literature relating to them 

 is admired by all students. I am very grateful to him for allowing me to include 

 this original matter in the present publication. On the facts determined by 

 Mr. Lambert, combined with an examination of certain copies of the work, I 

 have drawn up a collation for the use of librarians. 



F. A. BATHER. 



Wimbledon, 



24 April) 19 10. 



