The under part of the creature is still very imperfectly known: it had its central lozenge-shaped plate, like that on the under side of the Pterichthys, but of greater elegance, (see [Plate III.], fig. 3,) round which the other plates were ranged. "What an appropriate ornament, if set in gold!" said Dr. Buckland, on seeing a very beautiful specimen of this central lozenge in the interesting collection of Professor Traill of Edinburgh,—"What an appropriate ornament for a lady geologist!" There are two marked peculiarities in the jaws of the Coccosteus, as shown in most of the specimens, illustrative of the lower part of the creature, which I have yet seen. The teeth, instead of being fixed in sockets, like those of quadrupeds and reptiles, or merely placed on the bone, like those of fish of the common varieties, seem to have been cut out of the solid, like the teeth of a saw or the teeth in the mandibles of the beetle, or in the nippers of the lobster, ([Plate III.], fig. 4;) and there appears to have been something strangely anomalous in the position of the jaws—something too anomalous, perhaps, to be regarded as proven by the evidence of the specimens yet found, but which may be mentioned with the view of directing attention to it. "Do not be deterred," said Agassiz, in the course of one of the interviews in which he obligingly indulged the writer of these chapters, who had mentioned to him that one of his opinions, just confirmed by the naturalist, had seemed so extraordinary that he had been almost afraid to communicate it,—"Do not be deterred, if you have examined minutely, by any dread of being deemed extravagant. The possibilities of existence run so deeply into the extravagant, that there is scarcely any conception too extraordinary for nature to realize." In all the more complete specimens which I have yet seen, the position of the jaws is vertical, not horizontal; and yet the creature, as shown by the tail, belonged unquestionably to the vertebrata. Now, though the mouths of the crustaceous animals, such as the crab and lobster, open vertically, and a similar arrangement obtains among the insect tribes, it has been remarked by naturalists, as an invariable condition of that higher order of animals distinguished by vertebral columns, that their mouths open horizontally. What I would remark as very extraordinary in the Coccosteus—not, however, in the way of directly asserting the fact, but merely by way of soliciting inquiry regarding it—is, that it seems to unite to a vertebral column a vertical mouth, thus forming a connecting link between two orders of existences, by conjoining what is at once their most characteristic and most dissimilar traits.[M]
[M] These statements regarding the character of the teeth and the position of the jaws of the Coccosteus have been challenged by very high authorities. I retain them, however, in this edition in their original form, as first made nearly six years ago. In at least two of my specimens of Coccosteus the teeth and jaw form unequivocally but one bone—a result, it is not improbable, of some after anchylosing process, but which still solicits inquiry as not yet definitely accounted for. The matter of fact in the case is certainly one which should be determined, not analogically, but on its own proper evidence, as furnished by good specimens. As for the remark regarding the probable position of the creature's jaws, it was ventured on at first, as the reader may perceive, with much hesitation, and must now be regarded as more doubtful than ever. Its repetition here, however, will, I trust, be regarded as simply indicative of a wish on the part of the writer, that the question be kept open just a little longer, and that further examination be made. There is certainly something very peculiar about the mouth of the Coccosteus not yet understood, and singularly formed plates, connected with it, which have not been introduced into any restoration, and the use of which in the economy of the animal seem wholly unknown. [1850.—I have at length found a very perfect specimen of the nether jaw of Coccosteus, and am prepared to show that it was of a character altogether unique. It had its two groups of from six to eight teeth, (exactly where, in the human subject, the molars are placed,) that seem to have acted on corresponding groups in the intermaxllaries, and two other groups of from three to five teeth placed at right angles with these, direct in the symphysis, and that seem to have acted on each other. But though these unique teeth of the symphysis formed a vertical line of mouth, it joined on at right angles to a transverse line of the ordinary type, as the upright stroke of the letter T joins on to the horizontal line a-top.] Fourth Edition.
I am acquainted with four species of Coccosteus—C. decipiens, C. cuspidatas, C. oblongus, and a variety not yet named; and many more species may yet be discovered.[N] Of all the existences of the formation, this curious fish seems to have been one of the most abundant. In a few square yards of rock I have laid open portions of the remains of a dozen different individuals belonging to two of the four species, the C. decipiens and C. cuspidatus, in the course of a single evening. None of the other kinds have yet been found at Cromarty. These two differed from each other in the proportions which their general bulk bore to their length—slightly, too, in the arrangement of their occipital plates. The Coccosteus latus, as the name implies, must have been by much a massier fish than the other; and we find the arch-like form of the plates which covered its head more complete: the plate representing the keystone rests on the saddle-shaped plate in the centre, and the plates representing the spring-stones of the arch exhibit a broader base. The accompanying print ([Plate III.]) represents the Coccosteus cuspidatus. The average length of the creature, including the tail, as shown in most of the Cromarty specimens, somewhat exceeded a foot. A few detached plates from Orkney, in the collection of Dr. Traill, must have belonged to an individual of fully twice that length.
[N] A fifth species has been named C. maximus.
[CHAPTER IV.]
The Elfin-fish of Gawin Douglas.—The Fish of the Old Red Sandstone scarcely less curious.—Place which they occupied indicated in the present Creation by a mere Gap.—Fish divided into two great Series, the Osseous and Cartilaginous.—Their distinctive Peculiarities.—Geological Illustration of Dr. Johnson's shrewd Objection to the Theory of Soame Jenyns.—Proofs of the intermediate Character of the Ichthyolites of the Old Red Sandstone.—Appearances which first led the Writer to deem it intermediate.—Confirmation by Agassiz.—The Osteolepis.—Order to which this Ichthyolite belonged.—Description.—Dipterus.—Diplopterus.—Cheirolepis.—Glyptolepis.
Has the reader ever heard of the "griesly fisch" and the "laithlie flood," described by that minstrel Bishop of Dunkeld "who gave rude Scotland Virgil's page?" Both fish and flood are the extravagances of a poet's dream. The flood came rolling through a wilderness of bogs and quagmires, under banks "dark as rocks the whilk the sey upcast." A skeleton forest stretched around, doddered and leafless; and through the "unblomit" and "barrant" trees