the volume, and to correct the false ones,—it is necessary that the real vestiges of creation should be carefully investigated, and their order of succession ascertained. HIGH STANDING OF THE PLACOIDS.—OBJECTIONS CONSIDERED. We have seen that some of the Silurian Placoids were large of size: the question still remains, Were they high in intelligence and organization? The Edinburgh Reviewer, in contending with the author of the “Vestiges,” replies in the affirmative, by claiming for them the first place among fishes. “Taking into account,” he says, “the brain and the whole nervous, circulating, and generative systems, they stand at the highest point of a natural ascending scale.” They are fishes, he again remarks, that rank among “the very highest types of their class.” “The fishes of this early age, and of all other ages previous to the Chalk,” says his antagonist, in reply, “are, for the most part, cartilaginous. The cartilaginous fishes—_Chondropterygii_ of Cuvier—are placed by that naturalist as a second series in his descending scale; being, however, he says, ‘in some measure _parallel to the first_.’ How far this is different from their being the highest types of the fish class, need not be largely insisted upon. Linnæus, again, was so impressed by the low characters of many of this order, that he actually ranked them with worms. Some of the cartilaginous fishes, nevertheless, have certain peculiar features of organization, chiefly connected with reproduction, in which they excel other fish; but such features are partly partaken of by families in inferior sub-kingdoms, showing that they cannot truly be regarded as marks of grade in their own class. When we look to the great fundamental characters particularly to the framework for the attachment of the muscles, what do we find?—why, that of these Placoids,—‘the highest types of their class,’—it is barely possible to establish their being vertebrata at all, the back-bone having generally been too slight for preservation, although the vertebral columns of later fossil fishes are as entire as those of any other animals. In many of them traces can be observed of the muscles having been attached to the external plates, strikingly indicating their low grade as vertebrate animals. The Edinburgh Reviewer ‘highest types of their class’ are in reality a separate series of that class, generally inferior, taking the leading features of organization of structure as a criterion, but when details of organization are regarded, stretching farther, both downward and upward, than the other series; so that, looking at one extremity, we are as much entitled to call them the lowest, as the Reviewer, looking at another extremity, is to call them the ‘highest of their class.’ Of the general inferiority there can be no room for doubt. Their cartilaginous structure is, in the first place, analogous to the embryonic state of vertebrated animals in general. The maxillary and intermaxillary bones