name given it by the Forfarshire workmen. With another such flap spreading out in the contrary direction, and a periwigged head between them, we would have one of the sandstone cherubs of our country churchyards complete.

There occur among the other organisms of Balruddery numerous ichthyodorulites,-fin-spines, such as those to which I have called the attention of the reader in describing the thorny-finned fish of the lower formation. But the ichthyodorulites of Balruddery differ essentially from those of Caithness, Moray, and Cromarty. These last are described on both sides, in every instance, by either straight or slightly-curved lines, whereas one of the describing lines in a Balruddery variety is broken by projecting prickles that resemble sharp hooked teeth set in a jaw, or rather the entire ichthyodorulite resembles the spring of a wild rose-bush bearing its peculiar aquiline-shaped thorns on one of its sides. Buckland in his Bridgewater Treatise, and Lyell in his Elements, refer to this peculiarity of structure in ichthyodorulites of the latter formations. The hooks are invariably ranged on the concave or posterior edge of the spine, and were employed, it is supposed, in elevating the fin. Another ichthyodorulite of the formation resembles, in the Gothic cast of its roddings, those of the Diplacanthus of the Lower Old Red Sandstone described in pages 116 and 117 of the present volume, and figured in Plate VIII. fig. 2, except that it was proportionally stouter, and traversed at its base by lines running counter to the striæ that furrow it longitudinally. Of the other organisms of Balrud

ery I cannot pretend to speak with any degree of ertainty. Some of them seem to have belonged to he Radiata; some are of so doubtful a character hat it can scarce be determined whether they took heir place among the forms of the vegetable or animal kingdoms. One organism in particular, which vas at first deemed the jointed stem of some plant -esembling a calamite of the Coal Measures, was found by Agassiz to be the slender limb of a crustacean. A minute description of this interesting deposit, with llustrative prints, would be of importance to science : it would serve to fill a gap in the scale. The geological pathway, which leads upwards to the present time from those ancient formations in which organic existence first began, has been the work of well nigh as many hands as some of our longer railroads: each contractor has taken his part; very extended parts have fallen to the share of some, and admirably have they executed them; but the pathway is not yet complete, and the completion of a highly curious portion of it awaits the further labours of Mr Webster of Balruddery.

A considerable portion of the rocks of this middle formation in Scotland are of a bluish-gray colour: in Balruddery they resemble the mudstones of the Silurian System; they form at Carmylie the fissile bluishgray pavement, so well known in commerce as the pavement of Arbroath; they occur as a hard micaceous building-stone in some parts of Fifeshire; in others they exist as beds of friable stratified clay, that dissolve into unctuous masses where washed by the In England the formation consists, throughout

sea.

its entire depth, of beds of red and green marl, with alternating beds of the nodular limestones, to which

it

owes its name, and with here and there an interposing band of indurated sandstone.

The Cornstone formation is more extensively developed in Forfarshire than in any other district in Scotland; and from this circumstance the result of the writer's observations regarding it, during the course of a recent visit, may be of some little interest to the reader. About two-thirds the entire area of this county is composed of Old Red Sandstone. It forms a portion of that great belt of the system which, extending across the island from the German Ocean to the Frith of Clyde, represents the southern bar of the huge sandstone frame in which the Highlands of Scotland is set. The Grampians run along its inner edge, composing part of the primary nucleus which the frame encloses: the Sidlaw Hills run through its centre in a line nearly parallel to these, and separated from them by Strathmore, the great valley of Angus. The valley and the hills thus form, if I may so express myself, the mouldings of the frame, -mouldings somewhat resembling the semi-recta of the architect. There is first, reckoning from the mountains downwards, an immense concave curve,— the valley; then an immense convex one,―the hills; and then a half curve bounded by the sea. The illustration may further serve to show the present condition of the formation: it is a frame much worn by denudation, and-just as in a bona fide frame-it is the higher mouldings that have suffered most. Layer after layer has been worn down on the ridges, exactly