intentional purposes, we must argue upon principles that are logically and diametrically inconsistent in themselves, and at variance with fundamental laws of reasoning. I will now advert to an omission in Mr. Spencer's analysis of the sacrum, which overlooks one of the strongest proofs of intentional design afforded by that part of the spinal column. We have seen what was its general purpose and growth, and the process of its formation. We have now to note its variations in the male and the female skeleton. In the male, the sacrum, thus formed before birth, after birth answers to and performs its ultimate function of a comparatively rigid and inflexible piece of bone, and it is provided with no other special characteristic. In the female, on the contrary, there is a most remarkable adaptation of this piece to the function of maternity. While all the upper vertebræ of which this piece was originally composed are welded together after birth in the female as in the male, in the female the lowest segment of all remains for a certain time flexible relatively to the upper part of the sacrum, in order to admit of the necessary expansion of the pelvis during the passage of the infant from the womb of the mother. In the normal condition of females of all the vertebrate orders, this flexibility of the lower part of the sacrum continues while the period of possible maternity continues. If in any individual female it happens to be wanting during the period of possible conception, delivery can not take place without danger to the mother or the offspring, or both. Hence, in very bad cases, nature has to be assisted by extraordinary means. But in the normal condition of the female sacrum, this flexibility, so essential in the process of safe delivery, is always found, and its special purpose is known to every anatomist, while it has no existence in the structure of the male. Is this distinction to be accounted for by the same kind of reasoning that undertakes to account for all the other great distinctions between the related forms of male and female, which reproduce their kind by a common process of the sexual union, namely, that this division of male and female came about by a habit that resulted now in the production of a male and now in the production of a female, from tendencies that were ungoverned by any special purpose? Must we not conclude, however inscrutable are the causes that determine the sex of a particular infant, that the sexes themselves were specially ordained? And if they were specially ordained, how are we to account for the special construction and function of each of them, without the interposition of a special design? And when we find a structure in the female obviously designed for a special purpose, and not existing in the male, are we to conclude that some particular race of females, in some remote period of antiquity, among the countless generations of the vertebrata, found that this flexibility of the