48 DOUBTFUL SPECIES. Chap. II. 



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 



