IV 
INTRODUCTION. 
brings together in a condensed form the heads of information dispersed through the two 
vokmies. The nomenclature of the text has been preserved, and the range of the species 
in time carefully noted. My friend has likewise added — -first, a tabular list of tl^e 
genera, with their ranges in geological time ; secondly, a list of the genera and 
species described in Volumes I and II ; and thirdly, an Index to Volume 11. I have no 
doubt these valuable additions to the practical worth of the volumes will be as much 
appreciated by my readers as they are by their author, who tenders his very best thanks 
and warmest acknowledgments to his old and much valued friend for this kind and 
unsolicited contribution to his work. 
THOMAS WRIGHT, M.D., F.R.S. 
4, St. Margaeet's Teeeace, Cheltenham; 
15^7* Marcli, 1880. 
