Monograph of Old Red Fishes, describes under the name of Platygnathus Jamesoni a fragment showing the posterior portion of the body, together with the caudal and part of the dorsal and anal fins. From a careful examination of the specimen, which was long in our possession, and by comparing it with many similar fragments, it seems to be unmistakably a portion of G. nobilissimus, and as such we have classed it in our list. And here it may be observed that the sculpturing of the scales, varying in different parts of the same fish, and the fuller development of the fins in stronger or it may be male individuals, has frequently, and not unnaturally, led to the erection of new and unwarranted genera and species. In Dr Anderson's Monograph of Dura Den, a head of Glyptolemus Kinnairdi is figured and named as Diplopterus Dalglisiensis, and Agassiz is given as the authority for the generic name. A tooth of Dendrodus and some scales of Phyllolepis concentricus, both of large size, are also mentioned as having been found in these sandstones; but as no indication of such genera has ever appeared in any of the hundreds of slabs we have examined, we decline to include them in the list of Dura Den fishes.

We have witnessed the results of every important excavation since 1838, whether accidental, as those by the millowner or intentional, as those by the proprietor of the estate, by Lady Kinnaird, with the proprietors' consent, by the Committee of the British Association on two successive summers, or by the Literary and Philosophical Society of St Andrews; and in all, those in the preceding list were the only genera and species discovered, if we except a few doubtful and illegible fragments. That other genera and species may exist in the fossiliferous strata no one can gainsay; but, judging from the material already excavated, and bearing in mind that the scales of these fishes differ in

size and ornamentation not only on different parts of the body, but also according to age, sex, and individual growth, we have yet seen no good grounds for extending the list of Dura Den fishes beyond that which we have indicated. There is no graver error in palæontology, and none that retards the science more, than the founding of new genera and species on data which the luckier discoveries of another day may overturn. Such a practice has already been the bane of our science, and should on every fitting occasion be resolutely resisted.

But whatever the species, the state of preservation is for the most part quite astonishing. Not only is the general form of the fish well preserved, but the bones of the head, the teeth, scales, fins, and fin-rays are all in place, as if the creatures had been suddenly enveloped in the sandy matrix, and this before the slighest maceration, decay, or displacement had taken place. There they lie in hundreds within the space of a few square yards, and often overlapping and overlying each other, as if overtaken and destroyed by some sudden catastrophe. Genera differing so widely as Glyptolepis and Glyptolamus, and above all, Pterichthys, were not likely to live in the same shoal, and their indiscriminate admixture in a fossil state would seem to imply that they had been drifted together after death. And yet drift and entombment must have taken place immediately after life was extinct, for otherwise it is impossible to account for the extreme perfection of their preservation. Marine fishes may be destroyed in shoals by a sudden influx of fresh water; and vice versa, fresh-water species may be killed by an influx of salt water. Fishes passing suddenly from cold water to a hotter medium, or vice versa, are paralysed and destroyed. They may also be killed in myriads by the emanation of deleterious gases from submarine volcanoes; or poisoned in a similar way by the sudden influx

of noxious waters. They may be shoaled, till death ensues, during earthquake convulsions; or they may be cut off in lagoons from the main water, and there be covered up by drifting sands in the course of a few tides. In whatever way the different genera of Dura Den may have been brought together, it is evident that their death has been sudden, and that they have been as quickly sanded up and protected from drifting and decay. There is seldom any separation of parts-no mutilation by garbage-feeders-no wasting or obliteration by natural decay. Every part is in place and in form, every sculpture and ornamentation as perfect and distinct as if they had been newly taken from the waters. And now, after the lapse of ages, there they lie -pursuer and pursued-in their yellow cerement of stone, an instructive story to the naturalist, and a theme of wonder to the uninformed. Can mind grasp the measure of their antiquity, or indicate the succession of events since they disported in the waters of the old red sandstone sea? How many changes has this limited area of earthcrust the Dura Den of to-day-witnessed since these yellow slabs formed the soft yielding sands of a primeval sea-shore? Let geology attempt a reply.

And first, the Coal-formation, with its thousands of feet of sandstones, limestones, ironstones, shales, and coals, was deposited in a later sea that swarmed still more abundantly with life; whilst along its shores and estuaries there flourished that exuberant vegetation whose consolidated relics furnish that fuel so indispensable to the requirements of modern civilisation. What ages of growth and decay to form these successive seams of coal! What cons of waste and transport to pile up these thousand alternations of sandstones and fire-clays and shales! But these too passed away and while the old red sandstone and coalformation were here and there raised into dry land, a still

younger sea received the sands and marls of the New Red Sandstone epoch-an epoch marked by other forms of life and other conditions of existence. Again this passed, and while the new red, coal, and old red sandstone were still farther upraised, and constituted the continents and islands, another and newer sea received the muddy silts and limestones of the Lias and Oolite, and swarmed with other forms of fish-life, with myriads of cuttle-fishes (ammonites) and gigantic reptiles. These reptiles, with a few birds and lowly mammals, were then the lords of creation; and it may be that ages before Dura Den was hewn out of the rock, or Kemback Hill had been moulded into form, there and on the same spot the iguanodon, megalosaur, and hylæosaur sunned themselves on the slopes or cropped the foliage of the oolitic flora. But sea and land are continually though slowly changing place. The oolitic seas are upraised into dry land, and newer sea-areas receive the limy muds and zoophytic debris of the Chalk - formation. Land in the northern hemisphere has now a broader area, the seas are shallower and more circumscribed, and in these seas and lagoons are deposited the sands, gravels, and gypsums of the Tertiary era, with occasional skeletons of the birds and mammals that now begin to people the earth. At length the conditions of the tertiary period begin to change, in obedience to that incessant law of cosmical mutability; and the land over large areas in the northern hemisphere begins to sink beneath the waters. The currents of the ocean are changed, and now a cold and rigorous climate ensues. The land still subsides, and down its slopes and hill-sides the glacier grinds its way, and on the submerged surfaces the melting iceberg drops its burden of clay and boulders. This is the Glacial or Boulder-Clay epoch of geologists. Ages roll by; the land begins to rise again; newer currents are established; the climate grows

less severe; and ultimately, within the limits of appreciable change, the sea and land, with all their varied tenantry (vegetable and animal), begin to assume their existing aspects. The Howe of Fife is still a long narrow arm of the sea, replete with seals and aquatic birds;* the valley of Ceres is a large shallow lake; and its drainage finds its way over the sandstones and greenstones that lie between it and the estuary of the Eden. The land still ascends; Stratheden is a plain of lakes and marshes; the stream from Ceres Loch still deepens its channel through the soft yellow sandstones, drains the lake, and, cutting still deeper and deeper, forms at length the romantic Den of Dura.

Skin-clad savages—we know not of what race—now seek shelter in the caves of Dura, or erect their wigwams on the slopes of Blebo, fish in the streams, or hunt with stone - spear and arrow the reindeer and wild ox in the plains of the Eden. Another and stronger race succeed, drive the old savage from the field, erect their hill-forts on Clatto, fight their battles at Kemback, raise their cairns on Cairngreen, and burn their sacrifices within the Druidic circle of Dairsie. The Romans come, push the Pict and Celt to the unhospitable hills, take possession of the more fertile valleys, and raise on the sacred circle of stones at Chapelwell + a chapel and altar to their god of victory. Sore pressed by the Goths, the Romans must attend to their own matters at home, and Britain is abandoned. few, however, remain, and get amalgamated with the old Horestii of Fife; and by-and-by Culdee and Catholic missionary take possession of the Roman altar, and erect

A

* The remains of whales, seals, and arctic birds have been found in the post-glacial "brick-clays" of Stratheden.

+ All the names in the neighbourhood-Dairsie, Kemback, Kinnaird, Blebo, Clatto, Dura, Cairngreen, Chapel well and the like-bear ample evidence not only of the successive races who peopled the district, but even of the aspects of the country, and the events that took place.