Dear Sir

At last the Ent. Society have printed my paper & I am enabled to send you ⁠⟨⁠a⁠⟩⁠ copy according to promise.¹

I do not know whether the peru⁠⟨⁠sal⁠⟩⁠ will repay your trouble, & I cannot point out especial passages embodying the facts most useful & interesting to you; the⁠⟨⁠y⁠⟩⁠ are scattered over the whole,—perhaps the concluding observations & those under the head of P. Hierocles are most to the point.²

I think there are about 3 points of interest arising from the review of the species of Papilio—& the genus from the precision of the specific characters & the great amount of material existing in collections is well calculated to illustrate them.— These are

1   The derivation of the Amazonian fauna. I confess I was not prepared for the result to which I was obliged to arrive after a close examination of the species & their distribution—viz: that the Guiana region must ⁠⟨⁠ha⁠⟩⁠ve been the seat of an ancient & peculiar fauna transmitted through vast lapses of time; & that thence was derived the fauna of the Amazon valley.—³ Also that it was still so rich in endemic species. Surely I am right in deriving the conclusion that there can have been no great extinction here ⁠⟨⁠d⁠⟩⁠uring the glacial epoch.⁴

2   The widely different variability of species when under different local conditions in localities widely apart— Let us suppose 4 species A B C D living at localities 1 & 2. A will be not in the least modified: B constant at 1 will be instable at 2: C will have become changed at 2 in all its individuals, but the change is so small that all will admit the difference to be that of a variety: whilst D will have become changed so much more considerably at 2 that every author will treat the form as a perfectly good species. Yet all the points of difference between D1 & D2 are similar to those between B1 & B2 and ⁠⟨⁠C⁠⟩⁠1 & C2, only they are greater in degree or more numerous

3   The permanency of local varieties after they have become established. It is still the favourite argument of our best naturalists that varieties will always return to their normal form & that they will inter breed & produce fertile offspring. This argument is derived from the observations of varieties produced by domesti⁠⟨⁠cation⁠⟩⁠—a false guide—such varieties are too rapidly made, to be compared with the slow alterations of the whole organism which takes place in nature & affects, I have no doubt, at length the reproductive elements.— In the genus Papilio there is a set of local varieties all connected by fine gradations of differences; & yet in one well established case two of these varieties exist in contact & do not show the slightest tendency to amalgamate.—⁵ It is a case exactly parallel to what would be if we were to find in the wild state a series of graduated local varieties between the horse & ass;— I thought it likely I should find in the Natural History of the Horse & ass some data to prove the parallel & turned to a paper by Blyth lately published on the varieties of wild ass.⁶ I was surprised to find how little was satisfactorily known on the subject & how uncertain & vacillating is the state of our knowledge of the species & varieties of these conspicuous animals.

With ⁠⟨⁠re⁠⟩⁠gard to the varieties of species involving modifications of their reproductive elements, a learned entomologist friend of mine, M^r Baly, has found in the chrysomelidæ, what he calls specific differences in the male organs of generation;⁷ he finds they ⁠⟨⁠v⁠⟩⁠ary between very closely allied forms,—but then he reasons I think falsely,—he says that the fact of the difference in these organs proves distinctness of species & thus he is proving to be distinct species forms which all Entomologists had agreed to consider as varieties.— It is very amusing to read (In the proc. Ent^l. Soc. I think September or October las) that he had received a large series of Donaciæ from N. America,— there were many doubtful forms amongst them & he has applied the test of these organs to prove whether they are distinct species or no.⁸

I hope you will excuse this rather rambling letter & favour me with your opinion on my pap⁠⟨⁠er⁠⟩⁠ at your earliest convenience

Yours sincerely | H W Bates