263 



I must now beg leave to apply the above fact in corroboration of wl 

 conjecture hazarded in print a dozen years ago, and which has been 

 referred to by Mr. Coleman, from memory, not quite correctly. In the 

 same paper from which I take the short extract quoted above, that 

 gentleman writes thus : — " The data acquired in the course of the in- 

 vestigation of the flora of the county in question on the above plan, 

 may serve to correct the statement of Mr. Watson (in one of his 

 works, which the writer has not now at hand to quote with precision), 

 to the effect that a single square mile will be found to contain half 

 the species of a county. This, however, w r ill be found to be a con- 

 siderable overstatement, unless a square mile be selected containing 

 every variety of soil and situation." (Phytol. iii. 220). 



But on reference to the passage, as actually printed in one of my 

 earlier volumes, I do not find any positive statement, but simply a 

 conjecture on the subject; and the conjecture is only to the effect, 

 that a square mile may be found containing half of the species of a 

 county, without implying that any or every square mile " taken at a 

 venture" will contain so large a number. After showing that the 

 average number of species in twelve local floras for counties or lesser 

 tracts does not greatly exceed 700, I added the following remark : — 

 " On the average, a single county appears to contain nearly one half 

 the whole number of species found in Britain ; and it would, perhaps, 

 not be a very erroneous guess to say, that a single mile may contain 

 half the species of a county." (' Remarks on the Geographical Distri- 

 bution of British Plants,' pp. 41—42. 1848). 



Hewett C. Watson. 



Thames Ditton, August 3, 1848. 



BOTANICAL SOCIETY OF LONDON. 



Friday, August 4, 1848. — John Reynolds, Esq., Treasurer, in the 

 chair. 



The following donations were announced : — 



British plants from Dr. Mateer, Mr. Daniel Stock, Miss Griffiths, 

 Mr. Daniel Oliver, jun., Mr. P. Gray, and Mrs. Russell. Foreign 

 plants from John Ball, Esq. Part III. of Vol. 11 of 'Journal of the 

 Statistical Society of London,' presented by that Society. A complete 

 set of the 'Journal of the Pharmaceutical Society,' presented by that 

 Society. 



