That special substance, according to whose mass and degree of development all the creatures of this world take rank in the scale of creation, is not bone, but brain. Were animals to be ranged according to the solidity of their bones, the class of birds would be assigned the first place; the family of the Felidœ, including the tiger and lion, the second; and the other terrestrial carnivora the third. Man and the herbivorous animals, though tolerably low in the scale, would be in advance of at least the reptiles. Most of these, however, would take precedence of the sagacious Delphiniœ; the osseous fishes would come next in order; the true placoids would follow, succeeded by the Sturiones; and the Suctorii, i. e. Cyclostomi or Lampreys, would bring up the rear. There would be evidently no order here: the utter confusion of such an arrangement, like that of the bits of a dissected map flung carelessly out of its box by a child, would of itself demonstrate the inadequacy and erroneousness of the regulating principle. But how very different the appearance presented, when for solidity of bone we substitute development of brain! Man takes his proper place at the head of creation; the lower mammalia follow,—each species in due order, according to its modicum of intelligence; the birds succeed the mammalia; the reptiles succeed the birds; the fishes succeed the reptiles; next in the long procession come the invertebrate animals; and these, too, take rank, if not according to their development of brain proper, at least according to their development of the substance of brain.