Consequently, special creationists must fall back upon another position and say,--Well, but it may have pleased the Deity to form a certain number of ideal types, and never to have allowed the structures occurring in one type to appear in any of the others. We answer,--Undoubtedly such may have been the case; but, if so, it is a most unfortunate thing for your theory, because the fact implies that the Deity has planned his types in such a way as to suggest the counter-theory of descent. For instance, it would seem most capricious on the part of the Deity to have made the eyes of an innumerable number of fish on exactly the same ideal type, and then to have made the eye of the octopus so exactly like these other eyes in superficial appearance as to deceive so accomplished a naturalist as Mr. Mivart, and yet to have taken scrupulous care that in no one ideal particular should the one type resemble the other. However, adopting for the sake of argument this great assumption, let us suppose that God did lay down these arbitrary rules for his own guidance in creation, and then let us see to what the assumption leads. If the Deity formed a certain number of ideal types, and determined that on no account should he allow any part of one type to appear in any part of another, surely we should expect that within the limits of the same type the same typical structures should always be present. Thus, remember what efforts, so to speak, have been made to maintain the uniformity of type in the case of the fore-limb as previously explained, and should we not expect that in other and similar cases a similar method should have been followed? Yet we repeatedly find that this is not the case. Even in the whale, as we have seen, the hind-limbs are either altogether absent or dwindled almost to nothing; and it is impossible to see in what respect the hind-limbs are of any less ideal value than the fore-limbs--which are carefully preserved in all vertebrated animals except the snakes, and the extinct _Dinornis_, where again we meet in this particular with a sudden and sublime indifference to the maintenance of a typical structure. (Fig. 6.)[4] Now I say that if the theory of ideal types is true, we have in these facts evidence of a most unreasonable inconsistency. But the theory of descent with continued adaptive modification fully explains all the known cases; for in every case the degree of divergence from the typical structure which an organism presents corresponds, in a general way, with the length of time during which the divergence has been going on. Thus we scarcely ever meet with any great departure from the typical form with respect to one of the organs, without some of the other organs being so far modified as of themselves to indicate, on the supposition of descent with modification, that the animal or plant must have been subject to the modifying influences for an enormously long series of generations.