when struck fresh from the surrounding lime, reflects the prismatic colors, as of old; a huge Modiola still retains its tinge of tawny and yellow; and the fossilized wood of the forma tion preserves a shade of the native tint, though darkened into brown. But there is considerably less of color in the fossils of the Old Red Sandstone. I have caught, and barely caught, in some of the newly disinterred specimens, the faint and evanescent reflection of a tinge of pearl; and were I acquainted with my own collection only, imagination, borrowing from the prevailing color, would be apt to people the ancient oceans, in which its forms existed, with swarthy races exclusively. But a view of the Altyre fossils would correct the impression. They are enclosed, like those of Cromarty, in nodules of an argillaceous limestone. The color, however, from the presence of iron, and the absence of bitumen, is different. It presents a mixture of gray, of pink, and of

several minutes before either would give way; and when one does submit, imagination can hardly conceive the vindictive fury of the conqueror, who, in the most persevering and unrelenting way, chases his rival from one part of the tub to another, until fairly exhausted with fatigue. From this period an interesting change takes place in the conqueror, who, from being a speckled and greenish-looking fish, assumes the most beautiful colors; the belly and lower jaws becoming a deep crimson, and the back sometimes a cream color, but generally a fine green, and the whole appearance full of animation and spirit. I have occasionally known three or four parts of the tub taken possession of by these little tyrants, who guard their territories with the strictest vigilance, and the slightest invasion brings on invariably a battle. A strange alteration immediately takes place in the defeated party: his gallant bearing forsakes him, his gay colors fade away, he becomes again speckled and ugly, and he hides his disgrace among his peaceable companions.'

brown; and on this ground the fossil is spread out in strongly contrasted masses of white and dark red, of blue, and of purple. Where the exuvia lie thickest, the white appears tinged with delicate blue the bone is but little changed. Where they are spread out more thinly, the iron has pervaded them, and the purple and deep red prevail. Thus the same ichthyolite presents, in some specimens, a body of white and plum-blue attached to fins of deep red, and with detached scales of red and of purple lying scattered around it. I need hardly add, however, that all this variety of coloring is, like the unvaried black of the Cromarty specimens, the result, merely, of a curious chemistry.

cea.

CHAPTER XIV.

The Cornstone Formation and its Organisms. - Dwarf Vegetation. — Cephalaspides. - Huge Lobster. - Habitats of the existing CrustaNo unapt representation of the Deposit of Balruddery, furnished by a land-locked Bay in the neighborhood of Cromarty. Vast Space occupied by the Geological Formations. Contrasted with the half-formed Deposits which represent the existing Creation. Inference. The formation of the Holoptychius. - Probable origin of its Siliceous Limestone. - Marked increase in the Bulk of the Existences of the System. - Conjectural Cause.-The Coal Measures.-The Limestone of Burdie House. - Conclusion.

THE curtain rises, and the scene is new.

The myriads of the lower formation have disappeared, and we are surrounded, on an upper platform, by the existences of a later creation. There is sea all around, as before; and we find beneath a dark-colored, muddy bottom, thickly covered by a dwarf vegetation. The circumstances differ little from those in which the ichthyolite beds of the preceding period were deposited; but forms of life, essentially different, career through the green depths, or creep over the ooze. Shoals of Cephalaspides, with their broad, arrow-like heads, and their slender, angular bodies, feathered with fins, sweep past like clouds of crossbow bolts in an ancient battle. We see the distant gleam of scales, but the forms are indistinct and dim: we can merely ascertain that the fins are elevated by spines of various shape and pattern; that of some the coats glitter with enamel; and that others—the sharks of this ancient period bristle over with minute thorny points. A huge crustacean, of uncouth proportions, stalks over the weedy bottom, or burrows in the hollows of the banks.

Let us attempt bringing our knowledge of the present to bear upon the past. The larger crustacea of the British seas abound most on iron-bound coasts, where they find sheltering places in the deeper fisures of sea-cliffs covered up by kelp and tangle, or under the lower edges of detached boulders, that rest unequally on uneven platforms of rock, amid forests of the rough-stemmed cuvy. We may traverse sandy or muddy shores for miles together, without finding a single crab, unless a belt of pebbles lines the upper zone of beach, where the forked and serrated fuci first appear, or a few weed-covered fragments of rock here and there occur in groups on the lower zones. In this formation, however, the bottom must have been formed of mingled sand and mud, and yet the crustacea were abundant. How account for the fact? There is, in most instances, an interesting conformity between the character of the ancient rocks, in which we find groups of peculiar fossils, and the habitats of those existences of the present creation which these fossils most resemble. The fisherman casts his nets in a central hollow of the Moray Frith, about thirty fathoms in depth, and draws them up foul with masses of a fetid mud, charged with multitudes of that curious purple-colored zoöphyte the sea-pen, invariably an inhabitant of such recesses. The graptolite of the most ancient fossiliferous rocks, an existence of unequivocally the same type, occurs in greatest abundance in a finely-levigated mudstone, for it, too, was a dweller in the mud. In like manner, we may find the ancient Modiola of the Lias in habitats analogous to those of its modern representative the muscle, and the encrinite of the Mountain Limestone fast rooted to its rocky platform, just as we may see the Helianthoida and Ascidioida of our seas fixed to their boulders and rocky skerries. But is not analogy at fault in the present instance?

Quite the reverse. Mark how thickly these carbonaceous impressions cover the muddy-colored and fissile sandstones of the formation, giving evidence of an abundant vegetation. We may learn from these obscure markings, that the place in which they grew could have been no unfit habitat for the crustaceous tribes.

There is a little, land-locked bay on the southern shore of the Frith of Cromarty, effectually screened from the easterly winds by the promontory on which the town is built, and but little affected by those of any other quarter, from the proximity of the neighboring shores. The bottom, at low ebb, presents a level plain of sand, so thickly covered by the green grass-weed of our more sheltered sandy bays and estuaries, that it presents almost the appearance of a meadow. The roots penetrate the sand to the depth of nearly a foot, binding it firmly together; and as they have grown and decayed in it for centuries, it has acquired, from the disseminated particles of vegetable matter, a deep leaden tint, more nearly approaching to black than even the dark gray mudstones of Balruddery. Nor is this the only effect: the intertwisted fibres impart to it such coherence, that, where scooped out into pools, the edges stand up perpendicular from the water, like banks of clay; and where these are hollowed into cavelike recesses, and there are few of them that are not so hollowed, the recesses remain unbroken and unfilled for years. The weeds have imparted to the sand a character different from its own, and have rendered it a suitable habitat for numerous tribes, which, in other circumstances, would have found no shelter in it. Now, among these we find in abundance the larger crustaceans of our coasts. The brown edible crab harbors in the hollows beside the pools; occasionally we may find in them an overgrown lobster, studded with