643 



"The third volume of the ' Cybele Britannica ' will continue and 

 conclude the distribution of species treated singly ; and in so far it 

 will be simply a continuation and conclusion of the two former vo- 

 lumes. A second portion of this volume will be devoted to such cor- 

 rections and additions as increased knowledge may have rendered 

 necessary, in reference to the distribution of the species treated in 

 those former volumes. The distribution of the whole series of spe- 

 cies will thus be brought down to the end of the year 1851. If 

 sufficient space shall then remain, without rendering the volume 

 inconveniently bulky, a tabular summary will be introduced, designed 

 to compress the leading facts of species-distribution into a more con- 

 densed and selected condition, for the use of Botanical Statists. 



" Thus far, the three earlier volumes of Cybele Britannica' will differ 

 much from the fourth and final volume. In the concluding volume it 

 is proposed to treat the distribution of plants under a different aspect ; 

 that is to say, not each one singly and apart, but the whole taken in 

 connexion ; in order that their individual peculiarities of distribution 

 may appear in comparison and contrast, as reciprocal illustrations of 

 each other. 



" The causes that now continue the existing distribution of plants 

 over the surface of the earth, or those that have originally and gradu- 

 ally determined their distribution, are too wide in their influence, to 

 admit of being properly treated in a work devoted to the plants of 

 one small country, and to their distribution within that limited space 

 only. Should the Author have life and leisure to carry out his 

 present wishes, and enduring inclination adequate to the task, he 

 may perhaps write a ' British and Foreign Cybele, for the pur- 

 pose of tracing the distribution of British species over other parts of 

 the earth, and of showing the true relation borne by the flora of Bri- 

 tain to the floras of neighbouring countries. The causes or con- 

 ditions of their distribution might then appropriately find place and 

 room in a work of that more comprehensive, and necessarily less de- 

 tailed, character. His investigations have not hitherto led him to 

 adopt the current opinion (or, rather, mere guess) that the flora of the 

 British islands has been derived from the opposite countries of the 

 Continent, — at least, not to any greater proportionate extent, than the 

 floras of those countries may be said to have been derived from Bri- 

 tain. Interchange has most likely taken place ; Britain giving, as 

 well as receiving. 



" It is not expected that the fourth volume of ' Cybele Britannica ' 

 can be published within two years from the date of the present vo- 

 lume, if so early as only two years after. That contemplated fourth 



