48 
DOUBTFUL SPECIES. 
Chap. IJ. 
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 con¬ 
sidered 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 never¬ 
theless 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 sepa¬ 
rate islands of the Galapagos Archipelago, both one 
with another, and with those from the American main¬ 
land, I was much struck how entirely vague and arbi¬ 
trary 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 
