siders the beach to be more ancient than the Roman period, and Mr. Geikie, on the contrary, more recent, both appealing to the position of the Roman Wall at its termination on the western and eastern coasts as evidence of the correctness of their views. Who shall decide when such authorities differ? Perhaps, after all, it is an advantage to science that the point should not be decided ex cathedra-and I cannot but feel something of the satisfaction expressed on a former occasion by the Professor of Geology in one of our Universities, when referring to the controversy regarding the age of certain fresh-water strata in his neighbourhood-that there was a probability of a question being left which would afford matter for speculation to all future generations of students in geology.

Professor Nicol, in his description of the Geology of Cantyre,'to the accuracy of which I can bear a willing testimony-gives a brief description of this old coast line; which from the level of its inner limit above high-water mark, may be called "the thirty-feet beach." All along the coast the ancient sea-margin may be traced by a line of cliffs of various degrees of steepness, according to the nature of the rock; sometimes as a bank umbrageous with trees and shrubs; sometimes as a rocky cliff projecting to the water's edge, and again receding inland for several hundred yards. In many places this old coast-cliff is hollowed into caverns of all sizes and forms; and these caverns have been hewn not only in the softer beds of the Old Red Sandstone and Conglomerate, or even in the Mica-schist, but in such hard rocks as the porphyries of Davar Island, at the entrance to Campbelton Bay.

From the base of this cliff a slightly shelving terrace extends to the present sea-margin, on which are built most of the villages, as well as some of the ruined churches and graveyards, which probably date as far back as the 12th or 13th century. The terrace has also been taken advantage of with considerable judgment for laying out the roads which skirt the shore; and I venture to think no traveller can come away from that wild country without complimenting the inhabitants on the excellency of their roads, over which, on the darkest nights, a carriage may be driven at a rapid pace with the greatest safety; and, as an additional recommendation, I may add, that there are no turnpikes.

The surface of the terrace is often diversified by rocks, sometimes rising in isolated and fantastic masses above the level surface of the terrace, and resembling in form and features those at a lower level which are now subject to the full play of the breakers. So little altered, indeed, are these inland rocks from the skerries and seastacks of the coast in the immediate vicinity that, as Mr. Geikie observes, were you to strip them of their garniture of lichens and mosses, and tear away the shrubs and brambles which cling to their sides or spring from their tops, and in their place clothe them with a slaggy covering of sea-weed, limpets, and Balani, you might suppose they had only yesterday been lifted out of the waters of the sea.

1 Journ. Geol. Soc., vol. viii.

I venture to offer a few remarks on the several forms in which these monuments and vestiges of ancient sea-action present themselves.

Along the western coast, north of Machrihanish Bay, the rocks of Mica-schist (forming the fundamental rock of the country) assume the most fantastic forms, and their wrinkled and weather-beaten surfaces often bear the closest resemblance to the knotty stem of an old oak. The beds are often intensely crumpled, but are traversed by a system of joints, running generally in a north-westerly direction, and cleaving the rock in nearly vertical fissures of wonderful regularity (see Fig. 1). In the case of this rock the action of the sea has resulted, not in the formation of caves, but of chasms, hewn out along these joints, sometimes to a depth of 40 or 50 feet. One of the most striking of these fissures is represented in Fig. 1. It is bridged across for the road at the spot from which the sketch is

Fig. 1.-SEA-WORN FISSURES IN MICA-SCHIST, BEYOND THE PRESENT REACH OF THE SEA. RAISED COAST OF CANTYRE.

taken, and in looking up the vista between the two vertical walls, the impression conveyed is that the walls have been rent asunder, so like are they to each other, and so true is their parallelism. Such an impression, it need scarcely be stated, would be erroneous; the true explanation being, that the intervening portions of the rock have been swept away, The jointage has been here evidently the guide to the sea-action, and the waves, taking advantage of those places where a number of fissures, running close together in parallel planes, has offered to their action a line of weakness, have loosened and carried away block after block, till such chasms are formed as those here presented to us. We have only to step down a few paces to the actual shore where the waves are at work among the same rocks to observe the present mode of hewing out similar

fissures; but it is impossible to observe a fissure in these tough schistose rocks of the old sea beach of such dimensions as the above (about 150 feet in length, and 35 or 40 in depth) without being impressed with the conviction that the time required for this work must have been long indeed.

The caves which are found at intervals all round the coast, and which form a range of natural rock-hewn compartments at a level of 10 to 30 feet above the present tidal limits, are perhaps the most convincing of all the various evidences of ancient sea-action which can be adduced. These caves are hewn, not only in the softer strata of the Old Red Sandstone, but also in rocks of such firmness as the porphyries of Davar Island, at the entrance to Campbelton Bay. This island, which on the landward side slopes gradually down to the water's edge, on the opposite side is girt by a wall of rugged rock, rising vertically from a ledge which slopes gradually downward and terminates in a vertical cliff under low water. The wall above the ledge is honeycombed with fissures and caves in a position beyond the reach of the sea, and unquestionably referable to a past age. One of these caves has a double mouth, and is stated by Professor Nicol to be 130 feet in length, and was originally even longer, because the face of the cliff is itself being gradually worn backwards, as is attested by the blocks of rock which lie scattered over the surface of the sloping ledge, which are loosened by the past rains and spray, and carried off by the waves. Professor Nicol remarks upon the length of time which must have been necessary to excavate such a cave as this. He says: "Even though some fissure in rock, or softer vein of stone, may have determined the greater waste in this place, still the time required for its formation must have been enormous. It seems, indeed, almost impossible to estimate the number of ages spent by the waves in cutting out a cave of 130 feet in length in rocks of such hardness as the porphyries of Davar Island."

Caves in the rock-bound coast between Campbelton and Keill are of frequent occurrence. The Old Red Conglomerate in which they are for the most part excavated is, in itself, well calculated to astonish any one who, like myself, sees it for the first time. It is a "pudding-stone," in which the plums are often of the size of the largest mortar shells, reaching three feet in diameter. Yet are they always so smooth and rounded, that they must have been rolled about for a long time by the waves before they became imbedded. The stones and boulders consist of felspar and claystone porphyries (some like those of Davar Island) indurated grits and sandstones, white and coloured quartz, and more rarely granite, but (as Professor Nicol has observed) there are no specimens of the prevailing rock of the country-mica-schist. I could not, however, help remarking frequent examples of that peculiar "liver-coloured" quartzite which occurs so abundantly in the New Red Conglomerate of Central England, and the source of which is still so mysterious. Some of the caves at Keill, close by the spot where St. Columba 1 Geology of Cantyre, p. 422.

is supposed to have landed on the shore of Scotland (A.D. 561), are fine specimens, and each has its legend devoutly treasured in the memories of the inhabitants, and happily preserved from the possibility of oblivion by the pen of Cuthbert Bede. Further north, about three miles south of Campbelton Bay, is a cave held in

Fig. 2.-ST. KIERAN'S CAVE. RAISED COAST OF CANTYRE.

peculiar veneration by the men of Cantyre. It is the cave of St. Kieran, "The Apostle of Cantyre," and the traditionary preceptor of St. Columba himself (Fig. 2). To this solitary dwelling he was wont to retire at the intervals between his missionary journeys amongst the savage clans and roving barbarians of this wild region. It is hewn in Conglomerate, reaching inward to a distance of about 120 feet from the entrance. From the interior, the southern extremity of Arran appears, and the entrance has a rude resemblance to a loftily-pointed arch. At the entrance the floor of the cave is about 12 feet above the present high water level, but it gradually ascends inwards to a height of at least 30 feet. The roof reaches an elevation of about 40 feet above the floor, and the cave itself is truly of ancient date.

From an examination of the caves which came under my notice, where the entrance was pointed or arched, it became evident to me, that they always had their origin in a fissure or joint, which offered a line of weakness for the action of the waves. In any case, however, the work of excavation must have been a long and laborious one. The huge boulders as they became dislodged from their beds, were doubtless wielded with powerful effect by the waves in battering the sides of the fissure when once an entrance was made, and when we recollect that the lower portions of the cave were subject to this action for a longer period than the upper it is not difficult to account for the arched form of the interior.

In the cases above cited the conglomerate beds are highly tilted, but another kind, namely, flat-roofed caves, may be observed where the beds are horizontal. A good example of this class is afforded by a nearly isolated rock of Old Red Sandstone at the village of Ballochantye (Fig. 3); a rock, truly wave-worn, and now so far

Fig. 3.-CAVE IN OLD COAST-CLIFFS, BALLOCHANTYE, CANTYRE.

out of reach of the sea, that the village is built between it and the shore, at a lower level. In this case the sea has acted horizontally by working in a stratum softer than the others within its reach, somewhat after the plan adopted by coal-miners. The upper layers then give way until one is reached sufficiently firm to form the roof. In another part of the rock a hole has actually been pierced right through along the line of another softer layer of sandstone.

Though the very recent elevation of the land, the evidences of which we have now been considering, has added some millions of acres to the area of Western Scotland, it cannot be doubted that the present action of the sea tends year by year to narrow the terrace, and to obliterate the vestiges of ancient sea action. As the present sea cliffs and skerries are being worn back towards the former coast-line, the two have in some places become as one, and it is sometimes impossible to trace the dividing line. Still, for all we can say to the contrary, it is quite possible another elevation of the coast may take place before all traces of "the thirty-feet" beach have disappeared.

III.-ON A NEW CRUSTACEAN (EGER MARDERI, H. W.), FROM THE LIAS OF LYME REGIS, DORSETSHIRE.

THE

HE beautiful crustacean, forming the subject of this paper, which is represented of the natural size in the accompanying plate, was obtained by Mr. J. W. Marder, from the Lower Lias of Lyme Regis, in Dorsetshire.

It is the first British example of the genus Eger of Count Münster,' a well-known form in the Lithographic stone of Solenhofen, in Bavaria. The specimen, which is now in the Geological Collection of the British Museum, is exposed on a slab of soft Blue

1 Münster's Beiträge Zur Petrefacten-kunde. Bayreuth, 1839. Heft ii. p. 64.