CONTENTS 



PAGE 



I. Structure and Classification : 



(«) INTRODUCTORY ...... 1 



{h) PREVIOUS WORK AND PRESENT TREATMENT 



(c) GENERAL CHARACTERS OF THE SUBFAMILY 



MICROTIN^ ...... 5 



{d) THE EVOLUTION OF THE MICROTIN.E AND THE 



INTERRELATIONSHIPS OF THE GENERA . 26 



(e) KEY TO THE GENERA ..... 88 



(/) SPECIAL NOTES : 



1. THE EVOLUTION OF THE INCISOR TEETH 99 



2. THE EVOLUTION OF THE CHEEK-TEETH . 102 



3. THE DENTAL FORMULA OF THE MURID^ 124 



4. THE RANGE IN TIME OF BRITISH FOSSIL 



MICROTIN^ ..... 125 



II. Sy-stematic Revision of the Microtin.e . . 137 



