Chap. II.] DOUBTFUL SPECIES. 61 



or plant ranges over the same continent, or inhabits 

 many islands in the same archipelago, and pre- 

 sents 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 varie- 

 ties. 



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 use- 

 less 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 confessed 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 



