IV 



INTRODUCTION. 



brings together in a condensed form the heads of information dispersed through the two 

 vokinies. The nomenclature of the text has been preserved, and the range of the species 

 in time carefidly noted. My friend has likewise added— Jirst, a tabular list of the 

 genera, with their ranges in geological time ; second/?/, a list of the genera and 

 species described in Volumes I and II ; and thirdly, an Index to Volume II. I have no 

 doubt these valuable additions to the practical worth of the volumes will be as much 

 appreciated by ray 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. Margaret's Terrace, Cheltenham; 

 \f)th March, 1880. 



