occurred. Nor do I know that analogy is very directly opposed to the supposition that the column might have existed in the creature in its stony state. If two solid calcareous substances, quite as hard and dense as any fossil Belemnite, exist within the head of the recent cod and haddock, why might not one solid calcareous substance have existed within the body of an extinct order of cuttle-fish?

I have found considerable difficulty in classing according to their species, the Belemnites of the Lias. I soon exhausted the species enumerated as peculiar to the formation by Miller, and found a great many others. They divide naturally into two well-marked families, the specimens of a numerous family, that, like the Belemnite elongatus, are broadest at the base, and diminish as they approach the apex, while the specimens of a family considerably less numerous, like the Belemnite fusiformis, resemble spear-heads, in being broadest near the middle, and in diminishing toward both ends. In subdividing these great families, various principles of classification have been adopted. There are grooves, single in some species, double, and even triple, in others; extending from the apex downwards in some-extending from the base upwards in others; and these have been regarded by Phillips-the geologist who has most thoroughly studied the subject as constituting valuable characteristics not only of species, but of genera and formations. Miller took into account, as principles of classification, not only the general form, but even the comparative transparency or opacity, of the column,-marks selected in accordance. with the belief that the column was originally the solid substance it is now. The order furnishes, doubtless, its various marks of specific arrangement. I have even found

the hint borrowed from the architect, of taking the proportions of species by their diameters, not without its value. In measuring, for instance, four well-preserved specimens of the Belemnite abbreviatus, one of the bulkiest which occurs in our Scotch Lias, and whose average length is six inches, I found that two of the four contained. 5 diameters, one 5 diameters, and one 5 diameters; while another bulky Belemnite of the Scotch Oolite, not yet named apparently, whose average length is 3 inches, contains only 33 diameters, and strikes at once as specifically different from the others. Equally striking is the specific difference of the Belemnite elongatus, which contains from nine to ten diameters, of another nameless species which contains from twelve to thirteen diameters, - of another which contains from fifteen to sixteen diameters, of another, agreeing in its proportions with the Belemnite longissimus of Miller, which contains from eighteen to twenty diameters, of another which contains from twenty-three to twenty-four diameters, and of yet another, long and slender as a heckle-pin, which contains from thirty to thirty-two diameters. My rule of classification must of course be regarded as merely a subsidiary one. There are species which it does not distinguish. It does not distinguish, for instance the Belemnite sulcatus of our Scotch Lias, whose average length is six inches, from the Belemnite elongatus, whose average length is eight. Both agree in containing from nine to ten diameters, though in form and appearance they are strikingly different, the adjuncatus being much more pointed at the apex than the other, much more finely polished on the surface, and furnished with a deeper groove. As a subsidiary rule, however, I have found the rule of the diameters a useful one. It has enabled me to form a

numerous and discordant assemblage of specimens into distinct groups, the specific identity of which, when thus collected, is at once verified by the eye.

But the reader, unless very thoroughly a geological one, must be of opinion that I have said quite enough about the Belemnite. I may, however, venture to add further, that its place in the geological scale is not without its interest. The periods of the more ancient formations, from the older Silurian to the older New Red Sandstone inclusive, had all passed away ere the order was called into existence. It then sprung into being nearly contemporaneously with the bird and the reptile; and, after existing by myriads during the Oolitic and Cretaceous periods, passed into extinction when the ocean of the Chalk had ceased to exist, and just as quadrupeds of the higher order were on the eve of appearing on the stage, but had not yet appeared. Since the period in which it lived, though geologically modern, the surface of the earth must have witnessed many strange revolutions. There have been Belemnites dug out of the sides of the Himalaya mountains, seventeen thousand feet above the level of the sea.

COPROLITES OF THE LIAS.

Large coprolites of peculiar appearance, some of them charged with fish-scales of the ganoid order, are tolerably abundant; and they belonged, I have little doubt, to saurians. When bringing home with me, many years since, a well-marked specimen, I overtook by the way an acquaintance who had passed a considerable part of his life in Dutch Guiana. The thought did not at first occur to me of submitting to him my specimen. As we walked on together, he thrust his hand into his pocket to bring out his

handkerchief, and brought out, instead, a large mass of damaged snuff. "Ah," he exclaimed, "that roguish boy! I was standing with my neighbor, the shopkeeper, this morning, when he was opening up a cask of snuff that had got spoiled with sea-water; and his boy, seeing my pocket provokingly open I suppose, must have dropped in this huge lump! The joke seems a small one," he continued, "but it must be at least rather a natural one. The only other trick of the kind ever played me was by a South American Indian, on the banks of the Demerara: he dropped, unseen, into the pocket of my light nankeen jacket a piece of sun-baked alligator's dung." "What sort of a looking substance was it?" I asked, uncovering my specimen, and submitting it to his examination; “was it at all like that?" "Not at all unlike," was the reply; "it bore an exactly similar pale yellow tint, as if, like the dung of our sea-birds that swallow and digest fish-bones, it contained abundance of lime; and it was sprinkled over, in the same way, with the glittering enamelled scales of that curious fish the bony pike, so common, as you are aware, in our South American rivers."

INTRUSIVE DIKES OF EATHIE.

There are appearances in connection with the Lias of Eathie which seem well suited to puzzle the geologist, and which have, in fact, already puzzled geologists not a little. We find them traversed by intrusive dykes of what seems a grayish-colored trap, extremely obstinate in yielding to the hammer, and which stand up among the softer shales like the walls of some ruined village. They are trap-dikes in essential except one;every they occur in every possible angle of disagreement with the line of the strata: in

some places they inclose the shale in slim, insulated strips, as a river incloses its islands; in others they traverse it with minute veins connected with the larger masses, in the way in which granite is so often seen traversing gneiss; in yet others the limestone in contact with them seems positively altered; the blue nodule has, at the line of junction, its strip of crystalline white, and the shale assumes an indurated and veinous character; the dikes are, in short, trap-dikes in every essential except one; but the wanting essential is of importance enough to constitute the problem in the case; they are not composed of trap. Some of our mineralogists have been a good deal puzzled by finding crystals of sandstone as regular in their planes and angles as if formed of any of the earths, or salts, or metals, whose law it is to build themselves up into little erections correctly mathematical in every point and line; and they have read the mystery by supposing that these sandstone crystals are mere casts moulded in the cavities in which crystals had once existed. The puzzle of the Lias dikes is of an exactly similar kind: they are composed, not of an igneous rock, but of a hard, calcareous sandstone, undistinguishable in hand-specimens from an indurated sandstone of the Lower Oolite, which may be found on the shore beneath Dunrobin, alternating with shale-beds of the period of the Oxford clay. I succeeded in finding in it, on one occasion, a shell in the same state of keeping in which shells are so often found in the resembling rocks of Sutherland, but the species unluckily could not be distinguished. A common microscope at once detects the mechanical character of the mass; and I have learned that Dr. Fleming, after reducing a portion of it, sent him as an igneous rock, to its original sand, simply by