Preface ix 



information on the bryophytic flora of the Lancashire 

 sand dunes. 



The following gentlemen, other than members of the 

 committee, have very Mndly contributed photographs : 

 Messrs ^\. Ball, F. F. Blackman, C. J. P. Cave, R. H. 

 Compton, F. H. Graveley, F. F. Laidlaw, S. Mangham, 

 E,. Welch, and A. Wilson. 



The information on the distribution of crops is mainly 

 taken from the official " Returns of the Board of Agricul- 

 ture and Fisheries " and from the Agricultural Statistics 

 of the Irish Department of Agriculture and Technical 

 Education; to the officials of the Board the editor is 

 indebted for most courteously given supplementary in- 

 formation, involving considerable trouble, mth regard to 

 changes in the area of wheat land. 



The editor also desires to express his special iudebted- 

 ness to his colleague, Dr C. B. Moss, Avho, besides con- 

 tributing important sections of the book, has given 

 constant help and advice throughout'; and to Dr W. G. 

 Smith, the Secretary of the Committee, who has read a 

 considerable part of the proofs and contributed many 

 valuable suggestions. The editor is indebted to his wife 

 for undertaking the laborious task of constructing the 

 general index. 



The treatment adopted iu Part II is first to give a 

 general account of the various formations and associations 

 recognised, A^ith lists of species occurring iu them. The 

 plant-communities are then, in some cases, illustrated 

 by descriptions of special iustances. 



^ It is right also to mention that the concept of the plant-formation 

 and of its relation to the association, which forms the logical basis on 

 which the scheme of classification embodied in the book is constructed, 

 owes its present form to Dr Moss. Of. "The Fundamental Units of 

 Vegetation," A'ew Fhytologist, Vol. rx. p. 18, 1910. 



