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SUMMAEY. 



Although the species, pertaining to the whole of the archipe- 

 lagos, which are included in this catalogue, amount to 440, 

 nevertheless when the other forms, which have been treated as 

 ' varieties ' are taken likewise into account, the entire number 

 is raised to 558. I think it desirable to draw particular atten- 

 tion to this, because the mere fact of allowing certain organisms 

 to be registered as species and others as varieties, however con- 

 scientiously our conclusions may be arrived at, does not neces- 

 sarily imply that they fulfil the absolute conditions, in every 

 single instance, which we believe to be involved in those terms. 

 For although it is true that we use our utmost endeavom-s so 

 to sift the evidence, in each individual case, as to arrive ulti- 

 mately at a just conclusion, it is by no means demonstrable 

 that we are always successful in the attempt ; from which it 

 would appear to follow, that in a geographical enumeration 

 like the one which constitutes the subject-matter of the present 

 volume, every form tvhich is sufficiently ivell defined to be 

 easily recognized should be punctiliously pointed out, whatever 

 be the rank which we may think attaches to it ; and, having 

 done our best to indicate the affinities, and therefore the cor- 

 rect systematic position, of each separate form, we may fairly 

 be content to regard our own precise views on the abstract ques- 

 tion of ' varieties ' and ' species ' as binding upon no naturalist 

 who is not willing to accept them. I would desire, however, 

 not to be misunderstood, — for these remarks are by no means 

 intended to insinuate that the lines of demarcation between 

 species, when correctly interpreted, are ever, in my opinion, 

 really confused or doubtful (the exact opposite having always 

 been my firm belief) ; but for us to determine them aright is 

 quite another matter, and I am willing therefore to admit that 

 we may often be seriously mistaken in our endeavours to decy- 

 plier them. And it is on this account, more emphatically, that 

 I would wish to give a prominence almost as great to the many 

 forms which I have assumed, throughout the present treatise, to 

 represent varieties, as to those which seem better looked upon 

 (so far as I am able to judge) as species, properly so called. 



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