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Show 48 DOUBTFUL SPECIES. CHAP. II. That varieties of this doubtful nature are far from t be disputed Compare the several uncommon canno · . floras of Great Britain, of France or of the United States, drawn up by different botanists, and see what a surprising number of forms have been ranked by one botanist as good species, and by another .as mere van·e t I' es. Mr . H . C. Watson, to whom I he under deep obligation for assistance of all kinds, has marked for me 182 British plants, which are generally considered as varieties, but which have ~ll bee:n r~nked by botanists as species; and in. making t~s hst he has omitted many trifling varieties, bu~ which nev.ertheless have been ranked by some botanists as species, and he has entirely omitted several highly polymorp~c genera. Under genera, i~cluding the ~ost polymorphic forms, Mr. Babington gives 251 species, whereas Mr. Bentham gives only 112,-a 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 t~?se b~ds 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, as geographical races! Many years ago, when comparing, and seeing others compare, the birds from the separate islands of the Galapagos Archipelago, both one with another and with those from the American mainland, I was ~uch struck how entirely vague and. a~bitrary is the distinction between species and vanetws. 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 it cannot CllAP. II. DOUDTFUL SPECIES. 49. be doubte~ would be ranked as distinct species by man entomologists. Even Ireland has a few animals no~ generally regar~ed as varieties, but which have' been ranke~ as species by some zoologists. Several most experienced ornithologists consider our British red grou.se as only a strongly-marked race of a Norwegian species, whereas the greater number rank it as an u~:tdoubted species peculiar to Great Britain. A wide distance betw~en the homes of two doubtful forms leads many naturalists to rank both as distinct species· but what distance, it has been well asked, will suffic~? if that between America and Europe is ample, will that between t~e Continent and the Azores, or Madeira, or the .canaries, or Ireland, be sufficient? It must he admi~ted that many forms, considered by highly-competent JU~ges as varieties, have so perfectly the character· of sp~mes that they are ranked by other highly competent JUdges as good and true species. But to discuss whether they are rightly called species or varieties before an~ de~nition of these terms has been generau;· accepted, IS yamly to beat the air. Many o~ t~e cases of strongly-marked varieties o:r ~oubtfu~ spe~Ies well deserve consideration ; for several ln:ere~ting hnes _of argu~ent, from geographical dis ... tributwn, analog1cal variation, hybridism, &c., have ;een broug~t to bear .on the attempt to determine their ank. ~ will here give only a single instance,---the wel!-know~ on.e of the primrose and cowslip, or Primula vens and elatwr. These plants differ considerably in appearance; they have a different flavour and emit a ~~fferent od?ur ; they flow~r at slightl~ different periods ; ey gr.ow In so~ewhat different stations ; they ascend mountain.s to different heights; they have different geographical ranges; and lastly, according to very numerous experiments made during several years by D |