Now, in fact, by diligent search such intermediate links between well-recognized species have been found in some cases, especially in birds, on account of their great power of dispersal. Certain forms have long been known from widely-separated regions, and universally regarded as distinct species, as distinct as any. Then, by minute examinations of intermediate regions, a complete series of intermediate forms has been picked up. This has occurred not only in one case but in many cases, and not in birds only but in many other classes--examples increase with our increasing knowledge.[11] The only answer to such evidence is that _these are not true species_. Now, see the fallacy lurking here! They define species as ultimate elements of taxonomy, as distinct and without intermediate links, and then require us to find such intermediate links; and, finally, when with infinite pains some such links are found, they say: “Oh! I see; we were mistaken; they are only varieties!!” It is true that naturalists, when intermediate links are found, usually put all together as one species, but this they do purely for the sake of clearness of definition and description. It is freely admitted by the evolutionist that species are _now_ usually distinct and without intermediate links, these having been destroyed in the struggle for life. This will be fully explained in another chapter. It is also freely admitted that although intermediate links must have existed at one time, their remains are rarely found. The reason of this will also be explained hereafter. Nevertheless, in some cases, as already seen, we do find them still existing. Now, we add that in some cases, where they no longer exist, we find them in the form of fossil remains. The most remarkable example of this is found in the gradual changes in the forms of Planorbis in the fresh-water deposits of Steinheim, as shown by the admirable researches of Hyatt.[12] We shall discuss these also more fully in another place. Now, if there be any such links at all, however rare, then every objection to the derivative origin of species is removed.