Vili PREFACE. 
the Hydrozoa of the Cambrian and Silurian rocks. Since the early portion of the volume 
(pp. 4-14)! was printed, I have been compelled by the researches of Professors Lapworth and 
Nicholson, Mr. Hopkinson and others, to rearrange in part the Group Graptolithoidea. The 
old genus Graptolithus has thus been entirely recast and other genera have been greatly 
modified. The Flora of the Carboniferous Rocks, through Professor Williamson and Mr. 
Kidston, and the Cephalopoda (Tetrabranchiata) of the Silurian Rocks, through the able 
monograph by Professor F. Blake, M.A., have received material additions; and the 
investigations of Mr. J. W. Davis, of Halifax, have largely increased our knowledge of the 
Fishes of the Carboniferous Rocks. The SuppLrementary InpDEx (p. 465) fully attests the 
numerous additions which have come to hand since the printing of the volume began, and 
references are therein made to 409 genera, 305 of which are new, illustrating 1156 species. 
The species catalogued in this volume through the five divisions of Paleozoic time, as before 
stated, number 6022. It is hoped that only a few may have escaped notice, and that, if such 
omissions occur, they will be pardoned by those who have passed through the ordeal of critical 
research extending over many years and carried on after the hours devoted to official duties *. 
The publication of this Catalogue of the British Palzeozoic Fossils is wholly due to the 
liberality and consideration of the Delegates of the Oxford University Press, for which I beg to 
tender my sincere thanks. 
R. ETHERIDGE. 
14 CARLYLE SQUARE, CHELSEA : 
Aug. I, 1888, 
‘ See note on Monograptus, p. 394. 
* The-remainder of the Catalogue, comprising the Mesozoic and Cainozoic genera and species, to the number of 13,000, 
is completed in manuscript, and the history of all the known British fossils is thus brought down to the present year 
(1888). The pressure of departmental duties does not leave me sufficient leisure to prepare this work for publication, 
so as to render it available to those who might find it of equal value with myself in the prosecution of Paleontological 
research, 
