INTRODUCTION 



In the preparation of Part II. of the Monograph of British 

 Lichens I have incorporated, as far as possible, the work 

 previously done by Mr. Crombie, and the classification adopted 

 follows, for the most part, the main lines of that projected by 

 him in the first volume. Any discrepancies between the sequence 

 of orders and genera and that outlined in the Synopsis in Part I. 

 are explained where they arise. The " Natural Orders " under 

 which the genera are classified correspond with the " Families " 

 recognised by A. Zahlbruckner in Engler and Prantl's Pflanzen- 

 familien. In Mr. Crombie's Synopsis the " Families " represent 

 the first grade of division of the Lichens and are sub-divided into 

 series, tribes and genera. In Part II. the term " Natural Order " 

 has been employed to avoid confusion, and, at the same time, to 

 bring the Monograph into line with recent systematic methods. 



According to modern views, more importance is assigned to 

 the microscopic structure of the fruit than was allowed by 

 Nylander and Crombie in their scheme of classification. The 

 systematic value of the form, colour and septation of the spores 

 had, however, already been recognised by Massalongo and other 

 continental Lichenologists, and by Mudd in our own country. 



I wish to acknowledge my great indebtedness to the Staff of 

 the Botanical Department of the British Museum, especially to 

 Dr. Rendle, Mr. A. Gepp, and Mr. W. Carver, for advice and 

 assistance generously given during the progress of the work, 

 and to Dr. A. Zahlbruckner, of Vienna, who has kindly advised 

 me on some points of nomenclature. I have to thank Mr. A. W. 

 Dennis who brought to me the first specimens of Gongylia viridis, 

 collected by Mr. B. W. J. Starling. For further new or rare 

 specimens I am indebted to the Rev. D. Lillie, the Rev. W. 

 Johnson, and the Rev. H. P. Reader, and to Mes^'rs. E. M. 

 Holmes, J. A. Martindale, J. A. Wheldon and A. Wilson. I 

 wish also to thank Mr. P. Highley for the care he has shown in 

 making the drawings for the plates which have been expressly 

 prepared for this work. 



ANNIE LORRAIN SMITH. 



