vi INTRODUCTION. 
Professor H. G. Bronn’s great work, the /udex Paleonto- 
logicus, provided still more numerous references, incor- 
porating the notices of British forms with those of similar 
fossils occurring in other parts of the world; and in 1854 a 
second edition of Professor Morris’ Catalogue was published, 
still further extending the list, and including all genera 
and species at that time known. Except in the Paleozoic 
groups, which are treated by Mr. R. Etheridge in his Fosszls 
of the British Islands, Part i (1888), the considerable 
advances in British Vertebrate Palzontology during the 
last thirty-five years have not hitherto been systemati- 
cally catalogued. The scattered form, however, in which 
the numerous works and memoirs have appeared, renders 
such a record almost essential for further progress; and 
the object of the present volume is to supply this deficiency 
in the literature of the subject. 
Vertebrate fossils have been found in British strata of 
as early a date as any known in other parts of the world; 
unless, indeed, the ichthyolites from Ohio described by 
Professor E. W. Claypole are referable to a slightly lower 
horizon than the English Ludlow, as already maintained. 
The ventral shield of a Pteraspidian fish (Scaphaspis 
ludensis), now in the Museum of Practical Geology, was. 
long ago discovered in the Lower Ludlow of Leintwardine, 
by the late Mr. John Edward Lee, F.G.S. The Upper 
Ludlow Bone-bed has furnished undoubted fish remains. 
(e.g., Onchus and Cyathaspis), although some of the fossils 
in Sir R. I. Murchison’s collection, originally described 
as such, may have been truly referable to invertebrate 
animals, as remarked by M‘Coy. All the Silurian Verte- 
brata described and figured in the‘ Silurian System’ 
unfortunately seem to have been lost.* 
The Downton Sandstone, in the neighbourhood of 
Ludlow, has also yielded shields of Pteraspidian fishes, 
due chiefly to the exertions of the late Messrs. R. W. 
* R. I. Murchison, Quart. Journ. Geol. So¢., vol. ix, 1853, p. 16. 
