xiv INTRODUCTION. 
appear in two categories; and it should be explained that a considerable number of 
the plants indicated in the second column as having only European extensions actually 
reach North Africa. The term “ universal” is applied to those plants which spread 
into all three of the northern continents ; and it also includes the cosmopolitan species. 
With regard to the “ southern universal ” the majority extend into the tropics; and of 
the “temperate universal ” sixteen species recur (in the southern hemisphere) in America 
only, ten in Africa only, and thirteen in Australia and New Zealand only; while 
fifty-six are more widely spread in south temperate regions. Though the foregoing 
numbers can only be accepted as approximate, they convey a good idea of the wide 
distribution of the British Phanerogamic Flora, which does not contain a single well- 
marked endemic species. | 
STATISTICAL COMPARISON OF THE FLORAS OF LARGE AND WIDELY SEPARATED AREAS. 
In the ‘ Appendix’ (vol. iv. pp. 202-207) comparisons are made between the Floras 
of Mexico and Australia, and the relative positions of the natural orders shown, 
according to their predominance in species. No very special meaning or importance is _ 
attached to such comparisons ; yet they are exceedingly interesting, and teach something 
beyond mere numbers of species, especially to persons possessing a practical knowledge 
of the nature, size, duration, &c. of the plants constituting the various natural orders. 
It is thought, therefore, that an extension of such comparisons to a third area, that of 
British India, may be welcome. There are many similarities as well as diversities in 
the American and Asiatic areas: similarities in the altitudinal and latitudinal ranges 
of the two countries, and in‘a less degree in their climatal conditions; diversities in 
the direction of the principal mountain-chains, and consequently of the aspects of the 
slopes or exposures, and diversities in the land-connections, drainage, and coast-line. 
It would unduly lengthen this sketch to enter into further particulars on these -points, 
therefore a tabular view of the composition of the Indian Flora compared with those 
of Australia and Mexico* may follow here. This table was drawn up, with the 
assistance of Sir Joseph Hooker, from his ‘ Flora of British India’ as far as published, 
and from the Kew Herbarium and recent monographs, such as Engler’s ‘ Aracee’ and 
Baker’s various papers on petaloid monocotyledons. ‘The writer, however, is entirely 
responsible for the numbers of species of the genera of Orchidee, Scitaminee, Gramineae, 
and some smaller orders, whilst Mr. C. B. Clarke obligingly furnished the numbers of 
the Cyperacee f. At Mr. Salvin’s suggestion a column showing the position of the 
natural orders in the Flora of the World has since been added. 
* For shortness Mexico is employed here and elsewhere instead of Mexico and Central America. 
+ Owing to some mistakes in the figures, chiefly in the number of species of Quercus, discovered after the 
table was compiled, the percentages were calculated from a total of 13,647 instead of 13,700. The orders 
affected have been transferred to their proper positions, but it was not thought desirable to make any other 
alterations. 
