These birds are closely allied in appearance to the Thenca of Chile or Callandra of la Plata. ... In each Isld. each kind is "exclusively" found: habits of all are indistinguishable. When I recollect, the fact that the form of the body, shape of scales & general size, the Spaniards can at once pronounce, from which Island any Tortoise may have been brought. When I see these Islands in sight of each other, & del. 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 "inserted" undermine the stability of Species.