In a previous contribution to the Geological Magazine the opinion was put forward, based upon an examination of field evidence available in the neighbourhood of Largo, that the assumption of a Permian age for the old volcanoes of East Fife should no longer be sustained. It will be remembered by those interested in the matter, that whereas this district afforded remarkably clear evidence of contemporaneous volcanic action during Lower Carboniferous times, no confirmation was forthcoming of Sir A. Geikie's wholly different structural interpretation of an overlying unconformable sheet of post-Carboniferous ash. The purpose of this paper is to supplement the conclusions arrived at three years ago, and to note one or two additional field exposures that seem likewise to indicate contemporary eruptive activity among the Lower Carboniferous rocks of East Fife.

The object of this preliminary note is to inquire how far the marine mollusca can be used in correlating the Quaternary marine deposits in Britain.

It is worth while to examine the value and definition of certain of the older generic or sub-generic groups, for there is much difference in the usage of the terms, and in the interpretation of their rank and value. This is especially the case with Acaste and Phacopidella, for the author of the latter name wrongly included in it such forms as Ac. downingiae and others of a diverse type, though they differed in important particulars from the species Ph. glockeri Barr. which he chose as the type of Phacopidella as above observed (see Glockeria). Other new and old generic terms appear to have been also used in too broad a sense, and there is no general agreement as to their limitation.

The region lying along the southern border of the Canadian Shield, the St. Lawrence basin, to which by far the greater part of the field work so far performed in this vast area has been confined, is divided into four geographically separate sub-provinces, in each of which the succession of formations is so different that few positive correlations of either formations or unconformities in different sub-provinces can be made. It is probable, however, that all geologists familiar with this region are agreed that there is a palaeoplain at the base of the Huronian that originally at least extended over the southern part of the Canadian Shield. If the existence of this palaeoplain be assumed as established then there are two major problems in Pre-Cambrian classification in this region that remain unsolved: (1) What is the position of the pre-Huronian palaeoplain in the succession of formations present in the sub-province north-west of Lake Superior and in the Grenville sub-province? and (2) is there a second erosion plain within the pre-Huronian complex, and, if so, can it be used satisfactorily for the classification of the pre-Huronian into two major divisions equivalent in rank to the Huronian?

The purpose of this paper has been to point out (1) that there is no present agreement regarding the solution of either of these problems; (2) that the existence of a widespread unconformity within the pre-Huronian complex of the St. Lawrence province is, as yet, only a hypothesis, and (3) that there are only two logical courses to be followed in the classification of the Pre-Cambrian formations of the Canadian Shield, either to adopt the dual classification or to use it tentatively in the manner indicated in the accompanying table, until the existence of the second widespread unconformity is established or disproved. It may be suggested, however, that since considerable difficulty is being encountered in applying the dual classification even within the St. Lawrence province, it may be more practical to adopt the dual classification for the major divisions of the Pre-Cambrian notwithstanding the possible presence of an unconformity within the pre-Huronian complex.

In conclusion the writer wishes to express his indebtedness to his colleagues of the Geological Survey of Canada, W. H. Collins, F. J. Alcock, T. L. Tanton, and J. F. Wright, for criticism of the columns in the table of formations having reference to the different sub-provinces with which they are especially familiar.

The following investigation was undertaken not only with a general descriptive aim, but also to endeavour to ascertain how far correlation of isolated plutonic outcrops can be made by means of the study of the accessory minerals. It is in addition an attempt to supply further evidence bearing on the relative ages of the Jersey granites and diorites in view of the opinion of Dr. G. H. Plymen, based on field evidence, that the granites are of two ages, but both Pre-Cambrian, the Mont Orgueil and Gorey granite being the older.

On studying a topographical map of Lake Geneva, two characteristic features strike one at once. There is, first of all, the division of the basin into two parts of different orientation—the “Grand Lac” set almost E.W., and the “Petit Lac” deviated by about 60° towards the S.S.W. The inhabitants of the region have always distinguished between the “Grand Lac”, also called “Haut Lac”, and the “Petit Lac”. The former has a depth of 300 metres and consists of a single basin, the floor of which is remarkably flat whilst the second, separated from the other by a submerged ridge 66·3 metres below the surface, begins by a first fosse76·2 metres deep, followed by three others 70·1, 70·4, and 50·1 metres deep respectively. IfLake Geneva is considered as having a single origin, and if the theory of glacial overdeepening is adopted, it is very difficult to explain the ridge separating the two basins. On the other hand, the “Haut Lac”, taken alone, presents nothing abnormal, compared with other basins in whose formation glaciers have taken a large part.

The area described in this paper is about 5 miles east of Rhayader and 4 miles north of Llandrindod Wells. The igneous rocks come to the surface in two localities, namely Baxter's Bank and Caerfagu Mill. The former is approximately half a mile north of the main road from Rhayader to Pen-y-Bont, whilst the latter is situated immediately to the south of the main road and about three-quarters of a mile south-east of the village of Nantmel.

The petrography of the Plateau Deposits has been determined. They yield species both of local origin and of the general Haldon types.

The kyanite and staurolite present have been derived from the north.

The planation of the limestones was initiated during the Cretaceous period.

The raised beaches are of slightly different types, the Thatcher raised beach being later. They furnish evidence of a former greater thickness of the Plateau Deposits.

Modern beach deposits furnish some evidence of the distributive powers of certain minerals, and point to the existence of Triassic and Cretaceous sediments outside the Bay.

The genus Camarophoria was established by King in 1846 for certain Permian brachiopods bearing internal structures similar to those of the Pentamerids. The essential features were the presence in the ventral valve of a spondylium (“an arch-shaped process”) supported by a median septum (“medio-longitudinal plate”). “The arch-shaped process and its supporting or suspending plate correspond in every respect except in degree with the apophysary system belonging to the large valve of Pentamerus.” In the dorsal valve there is developed a high median septum supporting a well-developed spondylium (“spatula-shaped process”).

A well preserved specimen 46mm. long and 22·5mm. wide (Fig.17) was found by Mr. R. Cory near Catadupa. The body whorl is contracted below the suture and has ten varices which die away at the anterior contraction and are slightly acute at the shoulder; the anterior part of the shell has five wavy spiral ridges. A smaller and more delicate but poorly preserved form (Fig. 18), with similar but more anteriorly produced varices, occurs just above the Barrettia limestone at St. Ann's Great River and resembles specimens of L. crassicostata Stol. from Assam figured by Spengler (Pal. Ind., N. Series, vol. viii, mem. i, 1923, pl. iii, figs. 34a, and b). Another species of Lyria or Volutilites (Fig. 16) with elongated spire has about 7 coarse uneven varices on the body whorl and occurs as badly preserved casts in the Providence shales. It attains a length of 47 mm.

William Smith's known writings deal almost exclusively with the practical application of the principles he discovered and enunciated.

In my paper on “The Massive Chert Formation of North Flintshire” certain views were expressed which do not accord with conclusions stated in various Memoirs of the Geological Survey. The object of this paper is to support my views by further evidence.

Professor Gregory's kindly review of the Carlisle memoir raises once more the vexed question of the structure of the New Red rocks of that district. Two borings, one at Abbey Town and the other at Bowness, prove a thick series of variegated shales in the drift-covered western part of the area. A third boring proved red beds beneath the Lias at Great Orton. As Professor Gregory points out, the correlation of these red beds with the Abbey Town shales is uncertain. Though expressing the same caution, he had nevertheless previously adopted the correlation, his section through Great Orton, here reproduced, showing the beds at the two places as continuous. In what follows it will be easy to distinguish the evidence relating to Great Orton from that dealing specifically with the Abbey Town shales.

In furtherance of an intention expressed in a former paper (Geol. Mag., Vol. LXIII, 1926, p. 143), I propose, in this communication, to give some statistics of the anal variations in 542 cups, all of which are referred to the genus Ulocrinus. Additional details are also given of similar variations in 130 cups referred to Hydreionocrinus. Fifty of the latter have already been dealt with elsewhere (Trans. Geol. Soc. Glasgow, vol. xvi, pt. iii, 1917–18, p. 383), but to complete the survey of the anal area in the four groups of cups for the present, it is thought advisable to include them here. The classification here adopted is the same as that given for Eupachycrinus calyx and Zeacrinus konincki, namely:—

The Upper Silurian rocks of Lesmahago, Lanarkshire, have long been known to contain Arthropod remains. In the Kelvin-grove Museum, Glasgow, are a number of curious forms from the Logan Water Lesmahago, which Professor McNair was good enough to allow me to examine. In the hope of solving some problems presented by them, I obtained, through the kindness of the Keeper of the Geological Department of the British Museum, the loan of a specimen from the same locality, which forms the subject of this note. Instead, however, of solving any difficulties, the specimen presented a new problem.

A case is described of rhythmic banding by iron oxide in a rhyolitic tuff. The fine-grained tuff has acted as a medium for the production of Liesegang rings, the irregularity in the rings being ascribed to minute variations in the texture of the rock, naturally less homogeneous than a gel.

In the Quarterly Journal of the Geological Society for 1925 (Q.J.G.S., vol. lxxxi, p. 113) I discussed the conditions of deposition of the Stockdale Shales of Valentian age. I had intended to make a detailed study of the deposits of later Silurian age, but circumstances have prevented this. I propose to offer a few notes on the subject which may be of use to other observers.

The peculiar coral to be described below was collected by Mr. R. S. Allan, of New Zealand, at Yass, New South Wales. It has a superficial resemblance to Favosites but close examination shows it to be imperforate and to belong to the Chaetetidae. It shows so many characters of interest that it seems to merit a full description.