Throughout the western portion of the South Island of New Zealand there extends a series of high ranges made up very largely of unfossiliferous greywacke and argillite, with rarely limestone. Parts of these formations have been variously grouped as the Aorere and Mount Arthur series and considered to be of Ordovician age.

In a study of the rocks of the eastern end of the Newry Complex, the writer distinguished two contrasted groups of hybrid rocks— (i) the Slievegarron type, and (ii) the Seeconnell type—both of which are intimately associated with biotite-pyroxenite and biotite-peridotite. The Slievegarron hybrids comprise an augite-biotite-diorite series. The typical augite-biotite-diorite (1934, p. 611) is a highly undersaturated rock heteromorphous with certain varieties of orthoclase-basalt and leucite-basanite; it might equally well be described as biotite-essexite-gabbro. No further discussion of these rocks will be undertaken in this paper, but it seems desirable to point out that they should not be confused—as unfortunately they have been—with gabbro-diorite.

THE purpose of this paper is to present briefly some conclusions drawn from a study of the longitudinal profiles of rivers in the south of England. In the view of the authors, the study of such profiles affords an important though neglected method of attack on the vexed problems of Pleistocene chronology, and it bids fair also to throw light on certain larger geophysical topics, and particularly on the theory of eustatic movements of sea-level.

It was indicated in a previous paper (Geol. Mag., LXXII, 1935, p. 208) that the Scottish Lower Carboniferous crinoid fauna contains a number of species which have never been adequately described. In the present communication, ten of these are discussed, the remainder, another ten or eleven species, will be dealt with later. All the specimens except four were collected by myself many years ago, but it was only recently that the requisite leisure was found to develop and clean them thoroughly.

AT certain levels in the Coal Measures of North Wales a flood of fish scales and bones occurs, to the exclusion of almost every other fossil; at others only an isolated scale or tooth is seen. The area appears to be especially rich in fish remains, though possibly this is due to inadequate collecting in other areas. A summary of the succession in the Flintshire and Denbighshire portions of the coalfield is shown in the diagram on p. 483, while the area dealt with is shown on the map (p. 482).

The importance of accurate knowledge concerning the causes of composition zoning in plagioclases lies in the possibility that such zoning may throw light on the magmatic history of the rock of which the zoned felspar is a component. The interpretation of plagioclase zoning has been the subject of much speculation among petrologists, Phemister having recently contributed (1934) a valuable discussion of earlier work, together with certain new suggestions as to the probable causes of the reverse and oscillatory types. My own attention was drawn to oscillatory zoning while studying the Upper Devonian igneous complex of Marysville, Victoria (Hills, 1932, pp. 152, 153), and I found the hypotheses suggested by Phemister and by Harloff (1927) to explain this enlightening. Nevertheless, it seems to me that the real significance of some of the processes postulated by both these workers has not been correctly indicated, and that the mechanism proposed by Phemister to account for oscillatory-normal zoning is not theoretically possible. Since it is important that the physico-chemical basis of such hypotheses be sound, a discussion of Phemister's and Harloff's theories, and certain other possible causes of reverse zoning is given below.

Intensive study of the heavy accessory minerals and comparison of the suites of them occurring in igneous rocks has recently received much attention. In 1915 Rastall and Wilcockson examined the heavy accessories from granites of the English Lake District in connection with a study of the mineral constitution of certain sandstones. They found a wide variation in the accessory minerals of the granites, but a distinct similarity in those from all phases of the igneous mass.

I had not intended to reply to Professor Holmes's recent paper in the Geological Magazine, but the apparent confusion of mind which exists about the question of contrasted differentiation has led me to do so.

Some additional data are given regarding the “newer” intrusions of an area of which the main petrological features have been described elsewhere. The intrusions are:— (1) Aplites, pegmatites, quartz-veins, granodiorite porphyries, and biotite-granodiorites in or around the Newer Diorite. (2) A “porphyry” contaminated by cordieritic hornfels and having “clouded ” plagioclase “phenocrysts ”. Evidence is given that the “phenocrysts” have xenocrystic cores. (3) Quartz-felsites with cordierite, andalusite, and garnet, and granodiorite-porphyries, lying between the Newer Diorite and its roof of Ben Lawers Schist. The granodiorite-porphyries post-date the Diorite but the age of the quartz-felsites is uncertain. Contamination, and mechanical and chemical alteration, of the quartz-felsites are recorded. (4) Newer quartz-felspar-porphyries and lamprophyres, not obviously associated with the Newer Diorite.

THE Lower Cambrian genus Salterella, Billings, has lately received a good deal of attention in connection with the problem of the origin of the Cephalopoda. The genus, it may be remembered, was first described by its author as undoubtedly allied to Serpulites i.e. a worm-tube, but it was soon transferred by Billings himself to the pteropods. Barrande and Walcott also considered Salterella to be related to Tentaculites and Hyolithes. Clark (1925), who revised the genus, came to the conclusion that Salterella was a cephalopod, and not by any means a primitive type, but it did not seem to him to be ancestral to any subsequent form. Poulsen (1927) accepted this view, stating that the cephalopod characters were very conspicuous, but his later (1932) restoration of an East Greenland form, identified with S. rugosa from Labrador, is no more convincing than was Clark's restoration of S. conulata. Unfortunately, the genotype species of Salterella (S. rugosa Billings) is still incompletely known and I agree with Teichert (1935) that further investigation is needed before the real nature of Salterella can be held to be established. If the “septal necks” are still a doubtful feature and if the very existence of a “siphuncle” is open to question, as Teichert rightly says, it is clearly as premature to visualize Salterella as a possible forerunner of the holochoanites (Schuchert, in Schindewolf, 1929) as it is to connect the equally doubtful Volborthella with either holochoanites (Teichert and Kobayashi) or orthochoanites (Schindewolf, 1934).

The Ridgeway Fault may begin along the north margin of the Chaldon Anticline as mapped by Bristow (1855), but its existence there was doubted by Strahan. From the “bridge” at Holworth it certainly continues along the north margin of the Poxwell-Sutton Poyntz Anticline to Greenhill. Here it turns a double corner, the exact nature of which is problematical, and runs thence obliquely across and later along and parallel to the north limb of the Upwey Syncline to a point ½ mile west of Portisham, where it dies out in Kimeridge Clay. The total length from near Chaldon is 13 miles.

The cephalopods and stromatoporoid collected from Akpatok Island, Ungava Bay, N.W.T., in 1931, by Cox, are described by Foerste in this communication as follows:—

Endoceras coxi sp. nov., Endoceras sp. (resembling E. coxi), Endoceras akpatokense Foerste, Endoceras two spp., Shamattawaceras cf. ascoceroides Foerste and Savage, Orthoceras ungavense Foerste, Spyroceras sp. (resembling S. balteatum (Bill.) in some respects), Spyroceras cf. aquilonare Troedsson), Spyroceras wordiei Foerste, Spyroceras two spp., Huronia septata Parks, Westonoceras sp., and Beatricea undulata Billings.

Tentative correlations of the Akpatok limestones with other areas are drawn from this material. The greater part of the lime-stones appear to correlate with the Red River formation of Manitoba. The lowest horizons, containing Westonoceras, apparently correspond to part of the Nelson River formation of the Hudson Bay region; the intermediate horizon, with Shamattawaceras and Huronia, apparently to the Shamattawa formation of the same locality; while the horizon with Beatricea (650 feet above sea-level) is of Richmond age. The extent to which the remainder of the fauna, as yet identified, agrees with this is reviewed.

Since 1876, when McCoy described two specimens of tuberculated plates under the name Asterolepis ornata var. australis, placoderm remains have been known to occur in the Middle Devonian marine limestones of Buchan, Victoria, Australia. Some years later, another specimen was obtained from the Buchan limestones by W. H. Ferguson of the Geological Survey of Victoria, and was referred by Chapman (1916) to the genus Phlyctaenaspis. Chapman, regarding McCoy's specimens as cospecific with the new material, included all the remains in the species Phlyctaenaspis australis (McCoy), distinguishing the more complete specimen discovered by Ferguson as P. australis var. confertituberculata Chapman. As Phlyctaenaspis is a form typical of the Lower Devonian, its reported occurrence in the Middle Devonian seemed to warrant further investigation. I therefore undertook a re-examination of all the available material, which is now preserved in the National Museum, Melbourne, and spent some months in removing the matrix from Ferguson's specimen. The matrix is a hard carbonaceous limestone containing remains of Spirifer yassensis and other invertebrates, and it was found that dilute hydrochloric acid would dissolve away this matrix without seriously affecting the fish plates, although care had to be taken not to subject these to too long contact with the acid. When as much of the matrix as possible had been removed mechanically by grinding, the fossil was exposed by brushing the dilute acid on to the remainder with a camel-hair brush, and continually observing the result under a binocular microscope.

I wish to correct by 40 feet the position hitherto assigned to the outcrop of the Ballachulish Slide (or Lag as it is safe to call it) in one of its four easily accessible exposures on the shores of Loch Leven. The change does not appreciably affect the mapping as shown on Sheet 53 of the Geological Survey one-inch-to-the-mile map of Scotland, but it is of some importance on the ground. The locality lies on the north shore of Loch Leven, within a few yards of the main road, opposite a small cottage, midway between Callert House and Callert Cottage. A conspicuous little summerhouse is built on the eastern edge of the quartzite listed below. The dip of all the formations is very steep, so that the breadths of outcrop, measured at right angles to strike, correspond roughly with thicknesses. Details are as follows:—

The pre-Cambrian geology in Canada is in an unsatisfactory condition, due not so much, to disagreement regarding fundamental facts and history, as to words and the control they exercise upon ideas.

It is now about forty years since the completion of the late Sir Aubrey Strahan's Geological Survey Memoir on the Isle of Purbeck and Weymouth, published in 1898. All those who, like the present writer, have known the Dorset coast from boyhood and have carried Strahan's maps and memoir over most of the ground many times cannot have failed to learn from them lessons of incalculable value. They will have come to regard the memoir as a model of scientific method and of lucid presentation, a classic not to be questioned save in matters of palaeontology, now necessarily out of date.

ONE mile due east of Tantallon Castle, on the East Lothian coast, there stands a conspicuous tower or beacon. Its purpose is to afford an offshore warning to mariners. It has been constructed upon the seaward extremity of a northerly-extending ridge of volcanic ash or agglomerate. In recent years the rocks exposed here have been carefully examined by a well-known Edinburgh geologist, the late Mr. T. Cuthbert Day, and his results are reported in an interesting paper entitled “Volcanic Vents on the Coast, from Tantallon Castle eastwards to Peffer Sands, and at Whitberry Point” (Trans. Edin. Geol. Soc., xii, 1930, p. 213). Mr. Day thought that the ash and agglomerate lying south of the beacon represented the materials belonging to two contiguous but distinct volcanic vents of Lower Carboniferous age. To the twin orifices he applied the designation—“ The Car Double Vent.” In the northerly vent there occur two basaltic intrusions intersecting the pyroclastic rock. One of these, an irregular 4 ft. dyke, trends north-west hard by the easterly side of the beacon. The other, an oval plug covering 500 square feet, or thereby, is situated about 100 yards to the south-east. Both masses were determined petrographically by Mr. Day as “ dark red basalt with conspicuous dark crystals of augite, somewhat decomposed, but appearing under the microscope to approach a limburgitic type ”. It is in reference to these “ limburgitic ” intrusions that I present the following brief note, because, lately, I have discovered that they consist of leucite-basanite, a rock of basic felspathoidal character not previously known to occur in this country.

Between Kennedy's Pass, 4 miles south of Girvan, and Currarie Port, 3½ miles south of Ballantrae, the coast is occupied by a varied assemblage of igneous rocks that have a north-easterly strike and extend inland for several miles (Text-fig. 1). The most important members of this assemblage are a series of spilite lavas and two large outcrops of serpentine. In the present paper it is not intended to give a general description of these rocks, but to concentrate upon the age-relationship of the serpentine to the lavas and associated sediments, in which Lapworth and later workers discovered Arenig fossils.

During the course of several journeys from the port of Zeilah southwards across the Ban or Plain to Buramo on the Abyssinian frontier, collections were made of characteristic crystalline rock groups in the hope of elucidating to some degree the composition and early history of the district. Permission to publish these notes was kindly given by the Colonial Office.

The structure of the fronto-ethmoid shield of Osteolepis macrolepidotus Ag. is described fully for the first time, and the homology of the dermal bones is discussed. The most interesting feature is the recognition of the existence of a sensory-canal bone bearing teeth in the position of the premaxillary of Tetrapods, with which it is shown to be homologous; the nomenclature of the equivalent bones suggested by Säve-Söderbergh is discussed and revised.

The presence of a continuous cosmine sheet overlying several bones is emphasized, and the problem of growth of such a combination is brought out. It is shown that the problem can be solved by extensive resorption and redeposition of cosmine, and this hitherto unnoticed change is demonstrated in a number ofOsteolepids and in some Dipnoi. The results of the resorption are to free the bones of the head from the cosmine, and thus to expose the top of the true bone ; the new characters are those usually associated with different genera, usually placed in distinct families.

Finally it is noted that the resorption involves a general chemical change affecting cosmine all over the body, which it is suggested may be due to the release of an internal secretion, the whole process of resorption and redeposition of cosmine being cyclic and almost certainly seasonal, growth being therefore a seasonal change.