INTRODUCTION. xiii 
very pleasing to the senior author to see the new school attacking the live 
subject in so thorough a manner, and we hope that the present work will 
assist such in the most complete manner. In this volume we give an 
illustration of the subspecific characters of the Silver Gull, and we propose in 
the succeeding volumes to illustrate further such features when of sufficient 
import. 
GREGORY M. MATHEWS. 
TOM IREDALE. 
12th February, 1921. 
