]possessed of but a scanty stock of animals, tenanted by these birds, but slightly differing in structure & filling the same place in Nature, I must suspect they are only varieties.The only fact of a similar kind of which I am aware, is the constant asserted difference — between the wolf-like Fox of East & West Falkland Islds.If there is the slightest foundation for these remarks the zoology of Archipelagoes — will be well worth examining; for such facts [would "inserted"] undermine the stability of Species.