Origin of Species Variorum

↑ 6 blocks not present in 1859 1860 1861; present in 1866 1869 1872

Mr. Wallace, in several valuable papers lately published on the various animals, especially on the Lepidoptera, inhabiting the islands of the great Malayan archipelago, shows that they may be classed under variable and under local forms, under geographical races or sub-species, and as true representative species. The variable forms vary much within the limits of the same island. The local forms of the same species are moderately constant and distinct in each separate island; but when all such forms from the several islands are compared, the differences become so slight, numerous, and graduated, that it is impossible to define or describe many of them, though at the same time the extreme forms are sufficiently distinct. The geographical races or sub-species are local forms completely fixed and isolated; but as they do not differ from each other by strongly marked and important characters, "there is no possible test but individual opinion to determine which of them shall be considered as species and which as varieties." Lastly, representative species fill the same place in the natural economy of each island as do the local forms and sub-species; but as they are distinguished from each other by a greater, though not by a definite, amount of difference than that between the local forms and sub-species, they are almost universally ranked by naturalists as true species. Nevertheless, no certain criterion can possibly be given by which variable forms, local forms, sub-species, and representative species can be recognised.

→ certainly would 1861 1866

it cannot be doubted would 1859 1860

would certainly 1869 1872

surprising number of forms have been ranked by one botanist as good species, and by another as mere varieties. Mr. H. C. Watson, to whom I lie under deep obligation for assistance of all kinds, has marked for me 182 British plants, which are generally considered as varieties, but which have all been ranked by botanists as species; and in making this list he has omitted many trifling varieties, but which nevertheless have been ranked by some botanists as species, and he has entirely omitted several highly polymorphic genera. Under genera, including the most polymorphic forms, Mr. Babington gives 251 species, whereas Mr. Bentham gives only

112,—a

112,—

difference of 139 doubtful forms! Amongst animals which unite for each birth, and which are highly locomotive, doubtful forms, ranked by one zoologist as a species and by another as a variety, can rarely be found within the same country, but are common in separated areas. How many of

the

those

birds and insects in North America and Europe, which differ very slightly from each other, have been ranked by one eminent naturalist as undoubted species, and by another as varieties, or, as they are often called,

geographical races! ↑

Many

years ago, when comparing, and seeing others compare, the birds from the

closely neighbouring

separate

islands of the Galapagos

archipelago,

Archipelago,

~~both~~

both

one with another, and with those from the American mainland, I was much struck how entirely vague and arbitrary is the distinction between species and varieties. On the islets of the little Madeira group there are many insects which are characterized as varieties in Mr. Wollaston's admirable work, but which →certainly would be ranked as distinct species by many entomologists. Even

Ire- land

Ireland

has a few animals, now generally regarded as varieties, but which have been ranked as species by some zoologists. Several

~~most~~

most

experienced