cases, decide by a majority of naturalists, for few well-marked and
well-known varieties can be named which have not been ranked as species
by at least some competent judges.
That varieties of this doubtful nature are far from uncommon cannot be
disputed. Compare the several 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 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 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 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, 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 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 it cannot
be doubted would be ranked as distinct species by many entomologists.
Even Ireland has a few animals, now generally regarded as varieties,
but which have been ranked as species by some zoologists. Several most
experienced ornithologists consider our British red grouse as only a
strongly-marked race of a Norwegian species, whereas the greater number
rank it as an undoubted species peculiar to Great Britain. A wide
distance between the homes of two doubtful forms leads many naturalists
to rank both as distinct species; but what distance, it has been well
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