INTRODUCTORY EXPLANATIONS. '6 



the subject, remaining unpublished and unarranged among 

 the Author's notes in manuscript, or even confined to the 

 still more j)recarious keeping of his own personal recol- 

 lections. He therefore wishes and hopes to be enabled 

 to write a fourth volume, to complete a work on which he 

 has bestowed no small share of his time and attention ; 

 while fully aware that the completed work would still be 

 far from exhausting the subject. 



But in case any circumstance should prevent that con- 

 templated fourth volume from ever being written, the 

 three earlier volumes of Cybele Britannica may even 

 then be considered in the character of a completed 

 (though much narrowed) treatise on the distribution of 

 plants in Britain. It would still constitute an advanced 

 ground or foundation, upon which a more perfect con- 

 struction might be raised at some future time, and by 

 some other hand. The chief difference in the present 

 work would be, that the facts remained only in arranged 

 details, instead of having been first investigated and 

 shown m detail, and then grouped together connectedly, 

 to illustrate their geographical relations to each other. 



The ' London Catalogue of British Plants,' published 

 for the Botanical Society of London, is still used as an 

 Index to the series of species in the Cybele Britannica. 

 It will not be difficult to keep in recollection, that the 

 names and numbers of the species, in each successive 

 volume of this work, will be found to correspond with 

 those of the three successive editions of the London Ca- 

 talogue ; — the first volume, with the first edition, — the 

 second volume, with the second edition, — the third vo- 

 lume, with the third edition. Though the names and 

 numbers of the species are nearly uniform in the three 

 editions, progressive knowledge and altered views led 

 to some few changes therein, and additional species 



