“The fishes of the sea shall declare unto thee.”—Job.
Lord Bacon remarks, “Some men think that the gratification of curiosity is the end of knowledge, some the love of fame, some the pleasure of dispute, and some the necessity of supporting themselves by knowledge; but the real use of all knowledge is this, that we should dedicate that reason which was given us by God to the use and advantage of man.” The historian of the old red sandstone, Hugh Miller, to whose researches not only we, but such men as Murchison, Lyell, Ansted, Agassiz and others, are so exclusively indebted, is a philosopher in this last category. He does not hesitate to tell us, how, as a Cromarty quarryman “twenty years ago,” he commenced a “life of labour and restraint,” a “slim, loose-jointed boy, fond of the pretty intangibilities of romance, and of dreaming when broad awake;”[[35]] and how, as a quarryman, he ever kept his eyes open, to observe the results of every blow of the hammer, stroke of the pick, or blast of the powder; and finding himself in the midst of new and undreamt-of relics of an old creation, preserved in “tables of stone,” he adds his testimony to that of the great father of inductive philosophy, “that it cannot be too extensively known, that nature is vast and knowledge limited, and that no individual, however humble in place or acquirement, need despair of adding to the general fund.”[[36]]
We here enter upon a marvellous field of discovery. Hitherto the forms of life we have met with have all been invertebrate. The trilobite, something between a crab and a beetle, once revelling, in untold myriads, probably on the land as well as in the water, and of which two hundred and fifty species have been brought to light, is the highest type of life with which our researches have made us familiar. We are now to begin the study of fossil fish, and to their discovery, strange forms, and characters, this chapter will be specially devoted. It was once a generally received opinion among even the most learned geologists, that the “old red sandstone,” or the “Devonian system,” was particularly barren of fossils, but the labours (literally such, “mente, manu, malleoque”[[37]]) of Hugh Miller have proved the contrary. “The fossils,” he says, “are remarkably numerous, and in a state of high preservation. I have a hundred solid proofs by which to establish the proof of my assertion, within less than a yard of me. Half my closet walls are covered with the peculiar fossils of the lower old red sandstone; and certainty a stranger assemblage of forms have rarely been grouped together; creatures whose very type is lost, fantastic and uncouth, and which puzzle the naturalist to assign them even their class; boat-like animals, furnished with oars and a rudder; fish plated over like the tortoise, above and below, with a strong armour of bone, and furnished with but one solitary rudder-like fin; other fish less equivocal in their form, but with the membranes of their fins thickly covered with scales; creatures bristling over with thorns, others glistening in an enamelled coat, as if beautifully japanned, the tail in every instance among the less equivocal shapes, formed not equally as in existing fish, on each side the central vertebral column, but chiefly on the lower side, the column sending out its diminished vertebræ to the extreme termination of the fin. All the forms testify of a remote antiquity—of a period whose fashions have passed away.”[[38]]
The old red sandstone formation prevails in the north of Scotland, Herefordshire, north of Devonshire, part of Cornwall, and in Worcestershire and Shropshire. Our attention will be principally confined to Cromarty, whose romantic bay and high hills have long arrested the admiring gaze of the traveller. This was the scene of Hugh Miller’s labours and discoveries; this the great library in which he read the history of pre-Adamite ichthyolites[[39]] exposed not only to the light of day, but for the first time to the inspection of human eyes, by the sweat-of-brow toil of one of Scotland’s noble sons. Before we get into the hard names that must be connected with this chapter, let us hear Mr. Miller describe this library of God’s books that was so long his wonder and his study in Cromartyshire. “The quarry in which I wrought lay on the southern shore of a noble inland bay, or frith rather, with a little clear stream on the one side, and a thick fir-wood on the other. Not the united labours of a thousand men for a thousand years could have furnished a better section of the geology of this district than this range of cliffs; it may be regarded as a sort of chance dissection on the earth’s crust. We see in one place the primary rock, with its veins of granite and quartz, its dizzy precipices of gneiss, its huge masses of horneblend; we find the secondary rock in another, with its beds of sandstone and shale, its spars, its clays, and its nodular limestones. We discover the still little known, but very interesting fossils of the old red sandstone in one deposition; we find the beautifully preserved shell and lignites of the lias in another. There are the remains of two several creations at once before us. The shore, too, is heaped with rolled fragments of almost every variety of rock,—basalts, ironstones, hyperstenes, porphyries, bituminous shales, and micaceous schists. In short, the young geologist, had he all Europe before him, could hardly choose for himself a better field. I had, however, no one to tell me so at the time, for geology had not yet travelled so far north; and so, without guide or vocabulary, I had to grope my way as best I might, and find out all its wonders for myself. But so slow was the process, and so much was I a seeker in the dark, that the facts contained in these few sentiments were the patient gatherings of years.”[[40]]
Now with regard to the hard names to which we have just made allusion—names that, apart from their etymology, which is nothing more than “sending vagrant words back to their parish,” are enough to startle any one; names such as heterocercal, homocercal, cephalaspis, pterichthys, coccosteus, osteolepis, &c. &c.—why, they will all presently become plain, and, we hope, familiar to our readers. “They are,” says Hugh Miller, “like all names in science, unfamiliar in their aspect to mere English readers, just because they are names not for England alone, but for England and the world. I am assured, however, that they are all composed of very good Greek, and picturesquely descriptive of some peculiarity in the fossils they designate.”[[41]]
The rest of this chapter will be occupied with an account of the four most remarkable and characteristic fishes of this formation, to understand which a few preliminary remarks are necessary. Cuvier divided all fish into two groups, the bony and the cartilaginous; and these two groups he subdivided into two divisions, characterised by differences in their fins, or organs of locomotion, one of which he called Acanthopterygian,[[42]] (thorny-finned,) and the other, Malacopterygian,[[43]] (or soft-finned.) This concise arrangement did not, however, meet all the wants of the fish-students, and it was often practically difficult to know under which class to arrange particular specimens. More recently M. Agassiz has arranged fish, not according to their fins, but according to their scales; and simple as this classification may seem, it is one of the greatest triumphs of genius in modern times, inasmuch as all fishes extinct and existing, that have inhabited or are inhabiting the “waters under the earth,” may be grouped easily under the following four divisions:—
1. Ganoid Scale; as bony pike.[[44]]
2. Placoid Scale.[[45]]