the encrinites, star-fish, and shell-fish seem thus to have had a partial distribution in the waters of the period, the annelids or worms, the crustacea, and the fishes abounded throughout, and this in numerous and varied specific aspects. Trails and burrows occur in every division of the system, from mere thread-like windings on the surfaces of the strata to burrows in the sandstones as thick as a man's arm; and crustacea (trilobites and eurypterites) throng especially the lower division in strange and often gigantic forms. Indeed the huge lobster-like forms of these eurypterites-eurypterus, pterygotus, and stylonurus-with their long segmented bodies void of appendages, and their broad carapaces, like the kingcrab's, with limbs and jaws beneath, are characteristic features of the Old Red fauna. Ranging from three to six feet and upwards in length, with their toothed prehensile claws and oar-like swimming feet, no crustacean form has since equalled them in size, though few, perhaps, are more rudimentary in their structure. Like most articulated animals, these crustacea seem to have been readily dismembered by decay, hence their limbs and segments are frequently detached and scattered; and yet so wonderful has the preservative process been, even in the midst of dismemberment and de

1856, that the term "Devonian can never be legitimately substituted for that of "Old Red Sandstone." We have examined the strata of Devonshire from north to south and from east to west, and instead of finding the equivalents of the Scottish Old Red, we discovered in the Northern division one set of rocks that should be ranked with the lowermost Carboniferous, and in the Southern another that was perhaps contemporaneous with portions of the middle and lower Old Red. At all events, the rocks of Devonshire as a whole do not represent the Old Red Sandstone of Scotland, of Northern Europe, and North America as a whole; and hence the inappropriateness of Devonian as a substitute for the earlier and more descriptive term Old Red Sandstone. The designation may yet be found to be an appropriate one for a set of formations that apparently lie between the true Old Red and the Carboniferous proper; but to employ it as synonymous with what was originally understood as the Old Red Sandstone system is, in our opinion, an error and misapplication.

cay, that their egg-packets, or masses of spawn (known as Parka decipiens, from Parkhill in Fife, where first detected), are common throughout the lower flagstones. How imperishable the record, could we only lay it bare, that nature keeps of her bygone aspects and operations!

Strange and gigantic, however, as are these early crustaceans, they are comparatively recent discoveries and but little known, and it is chiefly though its fossil fishes, their numbers, variety, and beauty of preservation, that the system has become the subject of popular interest and investigation. As might be anticipated, these fishes differ considerably in the different portions of the system-those of the lower being chiefly small or moderate sized, covered with minute enamelled scales, and very generally armed with finspines; those of the middle portion, again, being fewer in number but larger in size, and protected by broad sculptured scales or plates; while those of the upper zone, though still covered with enamelled scales, assume more the character of ordinary fishes, both in their size and configuration. Throughout the whole, the bony enamelled scales and plates (the exo-skeleton of anátomists) is the prevailing feature, and all without exception are characterised by the heterocercal or unequally-lobed tail—the upper lobe extending in a bold and prolonged sweep, as in the existing sharks and dog-fishes. In Britain the great repositories of Old Red fishes have hitherto been the lower shales of Forfarshire, the lower and middle flagstones of Caithness and Cromarty, the middle sandstones of Moray and Banff, and the upper yellow sandstones of Fife and Roxburgh. In some of these localities they are crowded together in shoals, with every fin and scale in place as if overtaken and entombed by some sudden catastrophe; and we have seen a slab about the size of an ordinary writing-table, raised in Dura Den, Fifeshire, with upwards of fifty individuals upon it, belonging to

five separate genera, and varying in length from ten to thirty inches.*

It would be out of place in a sketch of this nature to enter into technical details, but it may be mentioned as of some value, and not difficult of comprehension, that the fishes of the lower zone, with fin-spines and minute lozengeshaped or but slightly-rounded scales, are known by such names as acanthodes (spiny), cheiracanthus (fin-spine), diplacanthus (double-spine), isnacanthus (slender-spine), parexus (ladder-spine), and so forth, in allusion to the character of their spines; that those of the same zone having the head enclosed in a bony shield or series of plates, are named cephalaspis (buckler-head) and pteraspis (buckler-wing); that those of the middle zone having their bodies enclosed in a bony case, somewhat like the living trunk-fish, are known as coccosteus (berry-bone), and pterichthys (wing-fish); while those of the same zone with ordinary scales and fins are spoken of as osteolepis (bony-scale), dipterus (double-fin), and diplopterus (twin-fin); and that those of the upper zone, with their variously-sculptured scales and head-plates, are known as holoptychius (allwrinkle), glyptolepis (carved-scale), glyptolemus (carvedthroat), and other such names, having allusion to some wellmarked and obvious distinction. There is nothing very puzzling in the names once their meaning has been explained and the objects to which they refer have been examined.

* At the instance of the British Association, and under the superintendence of the late Dr Anderson of Newburgh, and the Author, this and numerous other slabs of nearly equal richness were raised from Dura Den in 1860 and 1861; and could they have been rendered readily portable, slabs of double these dimensions, and with treble the number of specimens, could have been easily obtained. The genera were chiefly Holoptychius, Glyptolepis, Phaneropleuron, Glyptolomus, Glyptopomus, and Pterichthys. At Langlee on the Jed, the bony plates of the Pterichthys are so numerous, that they form a breccia several inches in thickness!

Indeed the local names for the living fishes of our own coast are often as puzzling and far less euphonious. Go to Cornwall and you hear one name, cross to Lincoln and you have another; proceed to Fife and you hear a third, or northward to Wick and you have a fourth-all requiring explanation, and, till explained, as unintelligible as the muchvituperated technicalities of the palæontologist.

Beyond fishes, we know for certain of no higher life during the period of the Old Red Sandstone. It is true that remains of reptiles and reptilian footprints have been found in the sandstones of Lossiemouth and Cummingstone in Morayshire, but there are doubts about the age of these strata-whether they be truly uppermost Old Red, or belong, more likely, to the New Red or Triassic. In this state of uncertainty it may be generalised (provisionally, of course, and having this doubtful instance fully in view) that the flora of the Old Red period, scantily and obscurely developed, consists mainly of sea-weeds, marsh-plants, clubmosses, ferns, and coniferous-looking trees; and that its fauna, on the other hand, taking all the divisions of the system as known in Europe and America, consists of corals, encrinites, star-fishes, polyzoa, shell-fish, crustacea, and fishes. We have thus no insects, no undoubted instance of reptiles, no birds, no mammals. No doubt the record is imperfect, and it cannot for a moment be supposed that geologists, in the few scattered patches they have examined, have detected all, or nearly all, of the Old Red Sandstone organisms. Indeed the existence of those already discovered necessarily implies the presence of others on whom they preyed, or by whom they were in turn preyed upon; and the links we have discovered in the chain of life, separated as they are, prove the existence of the missing ones as clearly as if they had been displayed before us. Still, notwithstanding all these facts and logical inferences, the flora and fauna of the

Old Red Sandstone curiously coincide in the main with all that geology knows of the chronological development of life on our globe, and we perceive in its discovered forms the gradually-ascending steps in the great systemal scale of vitality.

Such is a brief review of the Old Red Sandstone-a period during which vertebrate life made its decided appearance on our planet, and during the continuance of which several new distributions of sea and land were effected. We say new distributions of sea and land, for there is no other way of accounting for the differences that exist between its lower, middle, and upper portions without supposing that they were deposited in seas of different depths, and in seas that derived their sediments from different directions. And as these varying distributions of sea and land necessarily imply variations in climate and external conditions, we can readily perceive how the plants and animals of the lower portion differ from those of the middle, and these again from those of the uppermost division. Nature is incessant in her operations, and while the system of Waste and Reconstruction, described in our Sketch No. 2,' endures, new distribution of sea and land will be brought about in the course of ages, varying conditions of climate will be effected, and under the new conditions some plants and animals will shift their ground, some will flourish more luxuriantly, and others, again, become altogether extirpated. But this is not all under these ever-varying conditions, and as time rolls on, some forms of life seem to run their appointed course and die out, and other and newer forms, in the course of creation, seem to make their appearance. It is thus that some forms of life are peculiar to the Old Red Sandstone-that is, do not occur in earlier systems, and are not found beyond the close of the period. Many forms of