traditionary knowledge of the race, why should not this very growth of the sacrum have been designed, in order to produce, after the birth of the individual, that relative rigidity which would in this part of the vertebral column be useful to an animal destined to an upright posture of the whole skeleton and to the habits and life of a biped? And, if we extend the inquiry to other species, why should we not expect to find, as in the case of an oviparous vertebrate like the ostrich, a repetition of the same general plan of forming the spinal column, for the same ultimate purpose, with such a variation in the number of original segments that are to constitute the sacrum as would be most useful to that bird, thus establishing for the ostrich a sacrum that in a reptile or a fish would not only not be required, but would be a positive incumbrance? Upon the hypothesis of special creations of the different species of vertebrate animals, every one of Mr. Spencer's questions, asked as if they were unanswerable, can receive a satisfactory solution. Thus, he asks, "Why, if the skeleton of each species was separately contrived, was this bony mass [the sacrum] made by soldering together a number of vertebræ like those forming the rest of the column, instead of being made [aboriginally] in one single piece?" The answer is, that in the establishment of the process of gestation and fœtal growth, if a human artificer and designer could have devised the process, he would have selected the very one that now exists, for certain obvious reasons. First, he would have designedly made the process to consist, in the embryo, of a division of the substance which was to form the vertebral column in a continuous and uniform division into segments, because the whole column is to have at first the flexibility that may be derived from such a division. Secondly, when the time was to arrive at which the formation of the sacrum, with its practical continuity of a single piece, was to commence, he would select the number of the lower vertebræ that would make a sacrum most useful to the particular species of animal, and would weld them together so as to give them the relative rigidity and action of a single piece. But as the whole formation is the result of a growth of the sacrum out of a part of the slowly forming column originally divided into vertebræ, the marks of these separate vertebræ would remain distinguishable, while they would cease to have the mechanical action of separate vertebræ.