INTRODUCTION. 
In the present Catalogue I have endeavoured, as far as possible, to 
follow in the lines laid down by Professor W. H. Flower 'in respect 
to the nomenclature of species and genera, and in regard to general 
Systematic arrangement. A larger number of synonyms are, how- 
ever, introduced, because in the case of fossils there is at present, 
unfortunately, but little uniformity in nomenclature, and the same 
species is still quoted by different writers under different designa- 
tions. In the case of the less frequently employed synonyms 
references are not always given. For each generic and specific 
name adopted I have given, as far as possible, the place and date of 
its first occurrence, and in many of the less perfectly known forms 
references are added to figures or full descriptions. Great care has 
been taken in endeavouring to find the proper name of each genus 
and species. 
In regard to systematic arrangement, | have endeavoured to so 
modify that adopted by Professor Flower as to make it include the 
host of extinct forms which are here dealt with, as it would be 
inconvenient to be continually referring groups to an Incerta sedes. 
In the case of well-known forms very frequently no specific or 
generic characters are given; but in instances where there are a 
number of closely allied genera, or a large number of species be- 
longing to one genus, and distinguished by characters which are 
not always readily apparent, I have frequently added a short notice 
of some of the more important generic and specific characters which 
are applicable to fossils. These characters are more fully given in 
the case of imperfectly known forms; and in some instances indi- 
vidual specimens which are of more than ordinary interest are more 
or less fully described. Species which still exist are indicated by 
their names being printed in Old-English characters. 
1 Catalogue of Specimens of Vertebrated Animals in the Museum of the 
Royal College of Surgeons, part ii. (1884). 
