WCP1762

[1]

Parkstone, Dorset

Oct[obe]^r. 2nd. 1892

Dear Sir

Thanks for your letter & enclosure on Placostylus. I cannot accept your conclusions drawn from the distribution of one genus — & without any full knowledge either of its past history or modes of dispersal, — as at all certain. I have not asserted, as you say, an absolute land-connection between Australia & New Zealand, but only a very much closer approach.

But even a connection at such a remote epoch as I suggest (early Tertiary or Cretaceous) [2] might have been, & probably was before the genus Placostylus came into existence! Your omission of all reference to this essential point of date of origin of the genus, vitiates all your arguments as against my views. The existence of land-shells, rather abundantly, in all oceanic islands shows that they have some means of dispersal independent of land-connection, or even of near approach; hence no arguments from present distribution of land-shells can prove land-connection. [3] It is by each specialist assuming that land-connection is necessary to explain the distribution of his special group, that has caused such apparent contra^dictions in geographical distribution, and rendered it impossible to arrive at any sound conclusions as to the past changes of the earth.

I have endeavoured to show the fallacy of such assumptions both in my "Geog[raphical] Dist[ribution] of Animals" & in my "Island Life"; and you are only drawing conclusions similar to those which I have again & again shown to be invalid. In my chapter on the "Flora of New Zealand" [4] I have fully shown the tropical & melanesian element in the N[ew] Z[ealand] flora, and the chapters on "The Azores" and "Bermuda" as well as those on the "Galapagos" and "St. Helena", show ^how impossible it is to draw ^valid conclusions as to land-connections from similarity in land-molluscs.

Yours very truly | Alfred R. Wallace [signature]

C. Hedley Esq[uire].