the point here turns not upon absolute identity so much as upon close resemblance.  For those who, with Agassiz, doubt the specific identity in any of these cases, and those who say, with Pictet, that “the later tertiary deposits contain in general the debris of species very nearly related to those which still exist, belonging to the same genera, but specifically different,” may also agree with Pictet, that the nearly-related species of successive faunas must or may have had “a material connection.”  But the only material connection that we have an idea of in such a case is a genealogical one.  And the supposition of a genealogical connection is surely not unnatural in such cases—­is demonstrably the natural one as respects all those tertiary species which experienced naturalists have pronounced to be identical with existing ones, but which others now deem distinct For to identify the two is the same thing as to conclude the one to be the ancestor of the other No doubt there are differences between the tertiary and the present individuals, differences equally noticed by both classes of naturalists, but differently estimated By the one these are deemed quite compatible, by the other incompatible, with community of origin But who can tell us what amount of difference is compatible with community of origin?  This is the very question at issue, and one to be settled by observation alone Who would have thought that the peach and the nectarine came from one stock?  But, this being proved is it now very improbable that both were derived from the almond, or from some common amygdaline progenitor?  Who would have thought that the cabbage, cauliflower, broccoli kale, and kohlrabi are derivatives of one species, and rape or colza, turnip, and probably ruta-baga, of another species?  And who that is convinced of this can long undoubtingly hold the original distinctness of turnips from cabbages as an article of faith?  On scientific grounds may not a primordial cabbage or rape be assumed as the ancestor of all the cabbage races, on much the same ground that we assume a common ancestry for the diversified human races?  If all Our breeds of cattle came from one stock why not this stock from the auroch, which has had all the time between the diluvial and the historic periods in which to set off a variation perhaps no greater than the difference between some sorts of domestic cattle?

That considerable differences are often discernible between tertiary individuals and their supposed descendants of the present day affords no argument against Darwin’s theory, as has been rashly thought, but is decidedly in its favor.  If the identification were so perfect that no more differences were observable between the tertiary and the recent shells than between various individuals of either, then Darwin’s opponents, who argue the immutability of species from the ibises and cats preserved by the ancient Egyptians being just like those of the present day, could triumphantly add a few hundred thousand years more to the length of the experiment and to the force of their argument.