4 
Willis.— The Evolution of Species in Ceylon , 
is yet larger again. In the case of Common, a species is usually found to 
occupy the whole area suited to it (the island shows Wet and Dry, Warm 
and Cool zones), and is common therein, whilst Very Common is the 
same as to area, but the species is yet more abundant. These figures are 
the result of over seventy years’ work by many excellent botanists, and 
it is not to be expected that more than perhaps one per cent, of them will 
be found to be erroneous. In any case, as they are based on actual 
herbarium specimens, it is impossible to lower a species in the classification, 
and consequently the ‘ wides ’ must remain much more common than the 
average of the flora. 
In the second place, even if some could be shown to be erroneous, 
the figures are so numerous that a few alterations would make no difference 
whatever. Ninety ‘ wides’ might each be lowered a class and yet leave 
the rarity 3-0. To equalize the endemics and the ‘wides’ would need 
687 alterations in the former, each raising a species one class in the list, 
and 699 in the latter, each lowering a species one class, which we have 
just shown to be impossible. The mere fact that the figures come out in 
such remarkable arithmetical progression along the scales shows that they 
must on the whole be accurate, for the chances against such an arrangement 
turning up accidentally are inconceivably great. 
Now not only do the grand totals show these figures of rarity for the 
three groups into which we have divided the Ceylon flora, but (as might be 
expected from the way in which the law shows, almost page by page 
of the Catalogue) the figures for each family show the same thing, down 
to families with 14 endemic species, and the figures for the groups of 
families containing 12, 11, 10, 8 or 7, 6 or 5, 4 or 3, and 2 or 1 species 
respectively. These figures are given in detail in Table VI of the Phil. 
Trans, paper, and it will suffice to quote here the actual mean rarity of the 
endemic species in all these families or groups, which gives the remarkable 
figures 4-4, 4-3, 4-9, 4-4, 4-3, 4-5, 47, 4-4, 4-0, 4-2, 4-1, 3-9, 4-5, 4-5, 4-1, 
4-5, 4-4, 4-2, 3-9, 4-3, 4-0, 4-0, 4-1. If we arrange these in numerical 
order, we get 3-9, 3-9, 4-0, 4-0, 4-0, 4-1, 4-1, 4-1, 4-2, 4-2, 4-3, 4-3, 4-3, 4-4, 
4 - 4 , 4 - 4 , 4 - 4 , 4 - 5 , 4 \ 5 . 4 ’ 5 . 4 ' 5 > 47 . 4 ' 9 ■ 
Such numerical results as these call for immediate explanation, if such 
be possible. One cannot pass them by as of no importance, as has been 
the custom with the usual statistics of geographical distribution, which 
give so many per cent, of Leguminosae, and so many of Orchidaceae, &c., 
as occurring in the locality under consideration. But to explain them 
in harmony with the theory of Natural Selection appears to me quite 
impossible. The further explanation which I put upon them is open to 
dispute, but the facts themselves are incontrovertible, and, so far as I can 
see, are very seriously out of accord with Natural Selection. And if the 
Ceylon flora cannot be explained upon that theory, it at least raises 
