In a letter published in the March–April, 1942, number of this magazine I said I hoped to continue working on the problematical bodies found in rhyolite-ash in Malaya and first described by me in 1930. Further work has been done, but before giving the results I must mention the unusual sequence of events that has led up to the present paper. My identification of “rods, spheres, and club-shaped objects” as spongeremains in 1930 (the work was chiefly done in 1928) was then supported by Dr. M. Burton, who thought they came from marine sponges; but in February, 1942, he withdrew this support. In Annual Reports for 1937–1940 Mr. E. S. Willbourn, Director of the Geological Survey, Federated Malay States, recorded more outcrops of this ash and mentioned the discovery by Mr. H. D. Collings of stone axes in gravel of probably Mid-Pleistocene age below the ash. Supported by Dr. K. P. Oakley, Mr. H. D. Willbourn queried the problematical bodies being sponge-spicules.

During the past two years several core-borings have been put down in South Durham in order to prove extensions of the Productive Coal Measures. In passing through the cover of Magnesian Limestone, here up to 300 feet thick, quite the most arresting feature was the presence of innumerable cavities of irregular distribution. These are especially characteristic of the Lower Limestones, and are of all sizes from tiny geodes almost completely infilled with calcite to gashes which cut deep into the heart of the 6 in. core. They are usually lined with calcite in a variety of forms; far more rarely there are other minerals among which fluorite and barytes seem to be the most abundant.

Shirley and Horsfield (1940) in describing the Carboniferous Limestone of the Castleton-Bradwell area in North Derbyshire submitted evidence that the richly fossiliferous rocks of B2 age, the “Castleton reef knoll limestones lie with strong unconformity on the D1-D2 limestones, being piled against steep slopes or cliffs of Mid-Carboniferous age of at least 550 feet. The Nun Low limestones of P age follow with a similar relationship to the Castleton Limestones”.

In a recent paper (Geol. Mag., lxxix, 1942, 272), a single specimen from Coplow Knoll, Clitheroe, which differed from the commoner forms found there, was referred to the genus Amphoracrinus under the name of A. clitheroensis. Some time after sending this paper to the editor I found in my collection a smaller specimen belonging to the same species and still later another one, together with seven specimens belonging to a distinct though closely allied species. This additional material shows that both species differ in several respects from Amphoracrinus and the new genus Pimlicocrinus is now proposed for their reception.

1. A sequence of strata is determined in the Dogger of Upper Eskdale and its tributary valleys. The rocks fall into three main series, which are subdivided into groups.

2. The underlying Yeovilian sediments, originally included with the Dogger, are mapped and briefly described. The unconformity between them and the Dogger is emphasized.

3. The Dogger is marine throughout but only the oldest yields an adequate faunal assemblage, similar to that of the Glaisdale Oolite Series (upper opalinum). The greater part of the Dogger of this area is therefore younger than that of the Yorkshire Coast.

4. Chemical changes in the sea-water caused the deposition of siderite to characterize the earliest phase (Glaisdale Oolite Series). This was succeeded by a phase of dominantly chamosite deposition (the Chamositic Series) followed by a reversion to siderite deposition (the Ajalon Series).

5. Earth-movement controlled sedimentation over the area. During the first phase an eastern tilt to the region held the centre and west above or near sea-level, where it received no sediment. The second phase saw general depression with the accumulation of shallow water sediments. This was followed by uplift and erosion when a broad shallow valley was cut. Partial depression then flooded the valley with derived marine sediments.

The purpose of this paper is to discuss certain aspects of pre-Karroo (unfossiliferous) stratigraphy of Tanganyika and to make certain proposals, which are considered desirable in order to further geological research in East Africa and to aid in regional and detailed mapping. A summary of the unfossiliferous rocks, together with these proposals, changing the names of certain systems, is systematized in Table I. The suggestions embodied in this scheme are as follows:

Dehée (1929, p. 26) has pointed out that there has been much confusion and difficulty in distinguishing A. concentrica from A. (Cleiothyridina) roissyi, and Weller (1914, p. 473) referred to Davidson's too broad interpretation of that species. One impression [H. 251] from Poleshill which Whidborne figured (1897, pl. xviii, fig. 3) under the latter name does not possess the characteristic spinosity of A. (Cl.) roissyi, but agrees instead with A. concentrica which is a typical Devonian species characteristic of the Upper Devonian, as Dehée remarks who figures examples of it (1929, p. 26, pl. iv, figs. 4−6) from Etroeungt.

The Portencorkrie igneous complex, a trapezoidal area of plutonic rocks intrusive into Silurian sediments, is situated in the Rhinns district of Wigtownshire some sixteen miles south of Stranraer and about four miles north-west of the Mull of Galloway. It appears on the Geological Survey (Scotland) 1-inch Sheet 1, and lies within the Ordnance Survey 6-inch quarter-sheets Wigtownshire 33 S.W. and 37 N.W. To the north and south the igneous margin can be followed with fair accuracy, while to the east the boundary is obscured by drift. Westwards, the rocks pass beneath the Irish Sea.

In a recent study of the growth stages of Promicroceras marstonense (Currie, 1942), it was shown that apart from slight individual variations, the growth-ratios exhibited changes at certain stages, which are characteristic of the species. A similar investigation has now been carried out with material representing other species of Promicroceras, in order to ascertain how far there is general agreement within the genus and the extent to which any differences are typical of the various species studied.

Whidborne gave a composite description of certain specimens from the Upper Devonian of Pilton and other localities which he grouped together and ascribed to the Carboniferous species P. (Buxtonia) scabriculus Mart. (Whidborne, 1897, 170, pi. xx, figs. 16–18, pi. xxi, fig. 12), but he considered that it was difficult to distinguish some of them from those which he ascribed to Strophalosia productoides. We cannot agree with his reference of any of them to Martin's Carboniferous species. The best preserved and first example [H. 286] which he figured (1897, pi. xx, fig. 16) is a pedicle-valve from “Smoking House Lane”. It has a transversely subquadrate shape with subrectangular cardinal angles not produced; the body is strongly arched longitudinally but only moderately convex transversely, and it has a weak median longitudinal depression, but descends steeply on each side to the smalt ears; it is covered by regular continuous rounded costae of equal size, about fifty in number, some of which bifurcate at about one-third to two-thirds their length, and very few of them show any small swellings on their course as in P. scabriulus; a few faint narrow concentric rugae are traceable on the posterior third of the body producing weak coarse reticulation; the umbo is very broad, rounded and incurved, projecting over the hinge-line; the ears, which are much depressed but not sharply marked off from the body, are triangular in shape and are crossed by a few narrow concentric rugae which bifurcate somewhat irregularly before reaching the hinge-line; a few large coarse spinose tubercles or spine-bases lie near the junction of the body with the ears. This pedicle-valve is sufficiently preserved to indicate a distinct species, for which the name porteri is proposed.

The material to be described was collected in the Shotts-Newhouse area (Sheet 31) of the Central Coalfield from the mussel bands above the Shotts Gas and presumed Lower Drumgray Coals. These horizons are within the Ovalis Zone (Weir and Leitch, 1936, pp. 704, 707). Fossils from above the presumed Lower Drumgray Coal were collected from the waste tip of South Langridge Colliery; material from the Shotts Gas was obtained from the tips at Fortissat, Hassockrigg, and Hirstrigg collieries.

Before the Austins published their Monograph on Recent and Fossil Crinoidea, they issued to prospective subscribers an illustrated circular intimating the forthcoming publication of the work. Through the kindness of Professor W. T. Gordon, of King's College, London, I have a copy of this circular. It is in one sheet, printed on one side only and measures 7¼ in. by 9½ in. Over one-third of the upper part of the printed page is occupied by two specimen illustrations, “Platycrinites laevis (Miller)” on the left, and “Actinocrinites elephantinus (Austin)” on the right hand side. The genus Platycrinites was later fully described in parts 1, 2, and 3 of the Monograph, and a facsimile of the drawing of P. laevis of the circular is given on pl. i, fig. 1e of the Monograph. The illustration of Actinocrinites elephantinus Austin, however, does not seem to have been published in any work by the Austins prior or subsequent to part 8 of the Monograph, which was the last number to appear.

Several years ago I wrote a number of papers on the results of my investigations in a synclinal area near Megiddo, south-east of Mount Carmel, which I called “ the syncline of Megiddo ”. In the thick Eocene series of this syncline two distinct horizons of Lower and Upper Lutetian have been recognized. Above the Lutetian beds some patches of transgressive Upper Oligocene are preserved. Unfortunately the publications were based on investigations of only the north-eastern border of the whole synclinal region, further field explorations having been made impossible by the riots in 1936−39. In the summer of 1942 I renewed my fieldwork, which has led to a discovery of an Upper Eocene transgression over a probable Middle Eocene series.

The Palaeozoic rocks of the Girvan district have long been known for their rich faunal content, which has been studied by many palaeontologists. Trilobites are so abundant that they have been dealt with in a special monograph by Reed (1903−6). Since the publication of the monograph, however, continued collecting has made possible the description of further species and the amplification of many of the original descriptions; much of this has been accomplished by the publication of three supplements to Reed's monograph. The present paper is devoted to a consideration of the hypostomes of some Girvan trilobites. Professor A. E. Trueman has taken a keen interest in its preparation, and I desire to thank him for his very valuable assistance in correcting and improving the text; I must acknowledge again my indebtedness to Dr. F. R. C. Reed for the loan of literature.

Some remarks recently made by Dr. Rastall in the Geological Magazine have drawn attention to a present need for objective study of valley sculpture in tropical rain-forest regions. Pending the collection of further data in difficult terrains like the Malay Peninsula and the Owen Stanley Range of New Guinea we have available some well-reasoned theories that have been offered in explanation of the peculiar forms assumed by most Hawaiian valleys—forms that are perhaps peculiar only when judged by cool-temperate standards.

Many fossils in the older rocks have been distorted by pressure, and if only one specimen is available it is often difficult to be sure of its original proportions. Sometimes, however, there is a specimen which not only furnishes sufficient data for the determination of its original form, but can be made to yield a photograph in which the distortion is corrected. In his paper on “Slaty Cleavage” Harker1 showed how, in such cases, the distortion can be determined, and he referred to an earlier paper by Dufet2 in which the same principle is used, though in a different way. So far as I know the method of correcting the distortion photographically has not previously been employed.

Zaphrentoid faunas occur in the Middle and Upper Viséan of Great Britain, but have not been adequately described and so are difficult to distinguish. Probably the most fossiliferous of such Upper Viséan faunas are those found in the D2–3 shales and grey limestones with chert which occur near the top of the Lower Carboniferous beds of Derbyshire. A characteristic form in these faunas is that usually assigned to Zaphrentis costata (McCoy), a species imperfectly known and inadequately described. In 1937 I collected such forms from Cawdor Quarry, Matlock Bridge, Derbyshire, with the intention of identifying and redescribing the species. Since then sections have been made from the lectotype: these sections, however, are imperfect and a specific description based on them by Hill (1940, p. 137) is necessarily incomplete. The specimens from Cawdor include one which is similar to Z. costata but which shows successive contractions of the corallum and a change from straight to waved and corrugated major septa, a phenomenon possibly due to “gerontism”.

Among the most notable features of the geology of Yorkshire are two parallel structures known as the Cleveland and Market Weighton anticlines. Although they are parallel and not far distant, it has often been pointed out, and especially by Kendall and Lamplugh that these structures differ in almost every possible way. The Market Weighton axis has now no topographical expression at the surface, whereas the Cleveland axis forms the watershed of one of the most clearly developed river-systems of the country. The first and most obvious meaning of this is that the Cleveland axis moved during the Tertiary, while the Market Weighton axis did not. But the real fundamental difference goes much further back than that.

When recently on military duty in India, the writer was in correspondence with Mr. D. N. Wadia on the known distribution of granite within the ranges of the Himalaya, arising out of a statement by Mr. Wadia in his General Presidential Address to the 29th India Science Congress, 1942, on “The Making of India”. Therein it was declared (p. 7): “In these earth plications masses of crystalline igneous rocks, granites, from the depths of the earth, have been pushed up through the sedimentary cover and now occupy the central zone of highest elevations. The sublime snow-capped peaks of the Himalaya from Mount Everest to Nanga Parbat, all are built of this axial granite core,” etc.