been said, a band of limestone, and over the limestone a thick bed of yellow sandstone, in which the system terminates, and which is overlaid in turn by the lower beds of the carboniferous group. The limestone band is unfossiliferous, and resembling, in mineralogical character, the Cornstones of England and Wales, it has been described as the Cornstone of Scotland; but the fact merely furnishes one illustration of many, of the inadequacy of a mineralogical nomenclature for the purposes of the geologist. In the neighborhood of Cromarty the lower formation abounds in beds of nodular limestone, identical in appearance with the Cornstone;--in England similar beds occur so abundantly in the middle formation, that it derives its name from them;--in Fife they occur in the upper formation exclusively. Thus the formation of the _Coccosteus_ and _Dipterus_ is a cornstone formation in the first locality; that of the _Cephalaspis_ and the gigantic lobster in the second; that of the _Holoptychius nobilissimus_ in the third. We have but to vary our field of observation to find all the formations of the system _Cornstone formations_ in turn. The limestone band of the upper member presents exactly similar appearances in Moray as in Fife. It is in both of a yellowish green or gray color, and a concretionary structure, consisting of softer and harder portions, that yield so unequally to the weather, as to exhibit in exposed cliffs and boulders a brecciated aspect, as if it had been a mechanical, not a chemical deposit; though its origin must unquestionably have been chemical. It contains minute crystals of galena, and abounds in masses of a cherty, siliceous substance that strikes fire with steel, and which, from the manner in which they are incorporated with the rock, show that they must have been formed along with it. From this circumstance, and from the general resemblance it bears to the deposits of the thermal waters of volcanic districts which precipitate siliceous mixed with calcareous matter, it has been suggested, and by no mean authority, that it must have derived its origin from hot springs. The bed is several yards in thickness; and as it appears both in Moray and in Fife, in localities at least a hundred and twenty miles apart, it must have been formed, if formed at all, in this manner, at a period when the volcanic agencies were in a state of activity at no great distance from the surface.