We are indebted to the Trustees of the Carnegie Trust for the Universities of Scotland for a grant to cover the cost of the plates in illustration of this paper. We are also grateful to Mr. S. Fingland for the care taken in preparation of the photographs.

Although the Pachycormid fish Saurostomus esocinus was known only by part of a lower jaw from the Upper Lias of Baden when it was first named by Agassiz, its principal characters have since been revealed by many incomplete specimens from the Upper Lias of Würtemberg, France, and Yorkshire, and by a well-preserved fish from Ilminster, Somersetshire, in the Charles Moore Collection, Bath Museum. The internal skeleton of the trunk and the fins, however, have not hitherto been so well seen as in a nearly complete fish from the Upper Lias of Würtemberg, prepared by Mr. Bernhard Hauff and now in the British Museum.

Zoœcia strongly pyriporiform, very small, length about ·4 mm.; areas broadly speaking elliptical but with a strong tendency to have the upper end flattened rather askew to the central line, average length ·18 mm., breadth ·11 mm.; the side walls of the area bear about a dozen tubercles so small that their existence is only just recognizable under a 3 in. objective; a 1 in. objective shows them to be perforated; below the area there is typically (after the early stages) a small perforated boss placed centrally on the front wall, but when the front wall has to accommodate an oœcium the boss splits into two, often very massive, one on either side of the oœcium.

Some years ago I was asked to look through a collection of geological specimens in the Raffles Museum, Singapore, and found in a drawer two exceptionally large obsidianites. They were not labelled, and nothing could be ascertained about their history, but an assistant in the Museum said he thought they might have come from Kelantan, a State on the east coast of the peninsula. The weights of the two obsidianites were 464 and 316.4 grams. The former and larger of the two was entrusted to a local firm to cut in half, with the result seen in Pl. VII, Fig. 1. The photograph, nevertheless, shows that there is a group of vesicles in the centre. The photographs, which are natural size, also show that there is nothing unusual about the surface of these specimens (Pl. VII, Fig. 2).

Zoarium unilaminate, adherent.

Zoœcia fairly large, with very little external front wall; areas widely elliptical, flattened for a short way at the upper end and surrounded by a slender rim, average length ·5 mm., breadth ·35 to ·4 mm.

It is many years ago since Sir Archibald Geikie pointed out that the Tertiary basalts of the Western Isles of Scotland and North-East Ireland were remnants of plateaux built up of lavas extruded from fissures after the manner described by von Richthofen. In historic times fissure eruptions have taken place in Iceland, and in The Ancient Volcanoes of Great Britain a chapter is included on “The Modern Volcanoes of Iceland as illustrative of the Tertiary Volcanic History of North-Western Europe” (1, p. 260). Whilst little remains to be added in support of the very definite analogy exhibited in the nature of the lava streams themselves, the equivalent of the thin bands of red rock so typically intercalated in the Tertiary series has not been particularly examined, and I have visited Iceland in order to study the red beds themselves and search for their counterparts in the modern lava deserts.

Zoœcia separated by a distinct furrow, which passes into a deep crevice at the junction points, widely rounded below but tapering very considerably and almost to a point above, with areas of the same shape and upright rounded side walls thickening considerably below, and often developing something of an internal front wall; average length of area 28 mm., breadth 2 mm., but marginal zoœcia often run much larger.

The phenomenon of which this paper treats occurs in a basalt dyke exposed in a small quarry by the roadside north-east of Dippin, near the twelfth milestone from Brodick. This dyke runs from north-west to south-east, and is intrusive into the great teschenite (or crinanite) sill of Dippin. It is probably the one referred to in the Geological Survey Memoir on North Arran, South Bute, and the Cumbraes (1903), p. 119. It averages 12 feet in thickness, although it is extremely irregular, owing perhaps to the difficulty experienced in penetrating the tough, coarse, massive rock of the sill. The contacts are not plane, but about against the crinanite in a very intricate manner, sometimes along vertical or horizontal joints, sometimes along irregular surfaces unconnected with jointing. Both contacts show thin films of tachylyte, which, as the rock is quarried, are left adhering to the irregular surfaces of the sill rock. Another dyke-like mass, 1 foot thick, is seen in the same quarry, and is doubtless an offshoot from the larger dyke.

Cheilostomatous Polyzoa are anything but common in the Chalk exposed on the Norfolk coast between Cromer and Weybourne, and which I will call the Weybourne Chalk as it is best exposed in the Weybourne half of the area. It was only quite recently that I realized that the gradual accumulation of material had produced a sufficient volume to give some idea of the general nature of the fauna. The precise position of this chalk in the zone of B. mucronata cannot be fixed on physical data, but the Survey view that it is only a little way below the Trimingham Chalk is highly probable. It is therefore rather remarkable to find that the Membraniporæ include several new species, in addition to M. flacilla (ante, p. 338), which are unknown so far at Trimingham. It will be interesting to see if these, which I proceed to describe, prove to be characteristic of any definite range of chalk in the Norfolk Senonian. They must all be described as scarce at Weybourne.

Diagnosis.—Corallum massive and probably nodular. Corallites polygonal, often pentagonal, and, where the walls are not well defined, appear circular. Calices from 2 to 3 mm. in diameter; the width of cœnenchyma separating them varies from ·5 to 2 mm. Septa twenty-four in number, subequal; the trabeculæ are distinct in some and in others fused together. Pali rounded; they occur in three crowns, the primary pali being larger than the others. They are sometimes quite separate from the septa, and sometimes completely fused with the septal ends. Together with the columella they occupy a space equal to one-third of the diameter of the clayx. Columella fairly large, though somewhat irregularly developed. Occasionally it is so small as to appear papilliform, but it is generally clearly fascicular.

The subject of the present memoir occupies a distinguished position as lecturer and teacher of our science in the University of Cambridge, one which he has held for more than thirty years, and he is well known among geologists generally as a high authority on the Palæozoic rocks, his writings being recorded in the “Quarterly Journal” of the Geological Society (of which Society he has filled the offices both of Secretary and President). His name has also frequently appeared as the author of important papers in the GeologicalMagazink and other works.

There has recently been exhibited in the Gallery of Fossil Mammals at the Natural History Museum a restored skeleton of Stenomylus hitchcooki, Loomis, a ‘gazelle-camel’ from the Lower Miocene of Nebraska. This specimen (M 10969), which has been mounted in relief by Mr. L. E. Parsons, jun., includes portions of the skeletons of two individuals, but much of the dorsal region of the vertebral column and the ribs have been restored in plaster. The remains are from the Lower Harrison Beds (Lower Miocene) near A gate Springs, Co. Nebraska, where upwards of forty skeletons were collected in a small area. Many were complete and lay in such a position that they are believed to be the remains of a herd overtaken by floods and drowned.

I have been studying the zones of the Upper Jurassic clays for the last seven or eight years. Repeated delays from various causes have already diminished the value of the results, and as the work is now held up indefinitely it seems advisable to publish a summary of the conclusions to which I have come, in case the completion of the work may fall to other hands. Such a summary must necessarily be much more dogmatic than I could wish. I have to acknowledge my very great indebtedness, both direct and indirect, in connexion with this work, to Mr. S. S. Buckman.

The three principal ophiolithic groups of this region are those of Levanto, Monte Bianco, and Monte Penna, about midway between Spezia and Genoa, viz. north of Levanto, Sestri Levante, and Chiavari, at average altitudes of 300, 800, and 1,600 metres respectively. Like the Eocene ophiolithic group of Sestri Ponente and Isoverde, west of Genoa, they lie in the upper horizon of that formation, that is, in the fossiliferous (fucoids) albarese limestones and the argillaceous schists which rest on the Middle Eocene macigno sandstone as the lowest member of the Ligurian Eocene. The sedimentary and infolded ophiolithic groups consecutively aligned from the coast to the crest of the Apennines form a series of anticlines north to south, dipping west, with some transverse folds. The whole region is greatly contorted and brecciated; it is, moreover, profoundly eroded by torrents charged with calcium carbonate which has accelerated erosion and at the same time re-cemented breccia. Although the three groups are now separated, they are, together with the scattered islands north of the crest of the Apennines towards Piacenza in the Po Valley, only the remnants of an originally continuous formation of no less than 1,500 square kilometres or 600 square miles.

During the preparation and arrangement of a series of Lovenia forbesi from the Australian Miocene (presented to the Geological Department by Professor F. J. Cole), a peculiar interambulacral structure was displayed. Two of the specimens are severely weathered, with the result that their surfaces are smooth (except for the areolæ of the large tubercles), while the sutures are clearly outlined in dark brown across the pale background of the plates. In this way there is revealed the surprising fact that plate-crushing and resorption, of a type similar to that often found in Echinoid ambulacra, occur in four of the interambulacral areas. There is no corresponding development in the ambulacra.

In 1844 Carpenter [1] divided the fossils then known as Terebratula into two groups—a perforate group, having the test covered with minute pores, and an imperforate group (the Rhynchonellids). These perforations (see Plate III) correspond to tubular processes of the mantle.

As is well known, the skeleton or oldermass of New Zealand is largely composed of a mass of deformed sedimentary rocks, the precise ages of the members of which are in doubt but do not affect the problem under consideration. The most profound deformation of this vast sedimentary group took place in late Jurassic or early Cretaceous times during what may be termed the “Mesozoic orogenic period”, when probably a great mountain range came into existence.

The fluctuations which take place from time to time in the lengths of glaciers are extremely interesting to the glaciologist; for there are good reasons for believing that the meteorological conditions which give rise to the lesser oscillations of glaciers are generally of the same character as those which produced the great secular changes of climate which occurred in past ages.

The new material on which this paper is based has lately been received through Mr. D. Ferguson, who recently investigated the geology of the island, and collected the rocks described in an earlier paper. It consists of twenty-seven rock specimens from the south-eastern end of the island, between Cape Disappointment and Cooper Island, and nine specimens from Gold Harbour on the north-east coast between Cooper Island and Royal Bay. All these were collected by the staff of the South Georgia Co., Ltd., under the instructions of Mr. Th. E. Salvesen, managing director, of Leith.

The structures described below occur in rocks of a rather monotonous and generally uninteresting type; namely in sandstones, interstratified with masses of shale and mudstone, exposed near the centre of the Berwyn Anticline in parts of Denbighshire. The necessity, however, of examining every exposure, incumbent upon the Surveyor, has led me to pay attention to detail, and especially to certain phenomena that would appear to be of world-wide occurrence in sediments of all ages.