Chap. II.] DOUBTFUL SPECIES. 61 



hand, an animal or plant ranges over the same 

 continent, or inhabits many islands in the same 

 archipelago, and presents different forms in the different 

 areas, there is always a good chance that intermediate 

 forms will be discovered which will link together the 

 extreme states ; and these are then degraded to the 

 rank of varieties. 



Some few naturalists maintain that animals never 

 present varieties ; but then these same naturalists rank 

 the slightest difference as of specific value ; and when 

 the same identical form is met with in two distant 

 countries, or in two geological formations, they believe 

 that two distinct species are hidden under the same 

 dress. The term species thus comes to be a mere 

 useless abstraction, implying and assuming a separate 

 act of creation. It is certain that many forms, 

 considered by highly-competent judges to be varieties, 

 resemble species so completely in character, that they 

 have been thus ranked by other highly-competent 

 judges. But to discuss whether they ought to be called 

 species or varieties, before any definition of these terms 

 has been generally accepted, is vainly to beat the air. 



Many of the cases of strongly-marked varieties or 

 doubtful species well deserve consideration ; for several 

 interesting lines of argument, from geographical dis- 

 tribution, analogical variation, hybridism, &c, have 

 been brought to bear in the attempt to determine their 

 rank; but space does not here permit me to discuss 

 them. Close investigation, in many cases, will no 

 doubt bring naturalists to agree how to rank doubtful 

 forms. Yet it must be contested that it is in the best 

 known countries that we find the greatest number of 

 them. I have been struck with the fact, that if any 



