The original generic diagnosis is as follows:—

“Polypary cyathiform, composed of numerous independent and frequently bifurcating polypiferous branches, originating from the distal extremity of a short stem, which is likewise polypiferous and is terminated proximally in an irregular corneous expansion. Hydrothecae of the type of those of Dictyonema, biserial, sub-alternate.

“The chief peculiarity of this genus is afforded by the character of the stem, which is identical in every respect with the main branches, and, like them, is denticulate or polypiferous throughout the whole of its extent. It commences proximally in a flattened expansion, with irregular or frayed-out edges, possibly the remains of a disk or bulb of attachment.

“The mode of branching is rigidly dichotomous, the first two branches being formed by the sub-division of the main stem itself. Each arm branches and rebranches again and again in the same manner, at frequent and close intervals, composing an elegant cyathiform or fan-like polypary, very symmetrical in form. The branches retain their original width to their final division, which gives rise to two minute branches less than one-tenth of an inch in length.

The following notes have been recorded with the idea of showing that a field relationship exists between true chert veins or aggregations, and certain igneous intrusions. Beyond the fact that the cherts have been formed probably as the result of some hydrothermal agency, usually associated with, and occasionally the result of, volcanic episodes, it is not possible to enter more fully into the geological origin of this form of silica. Microscopic fossils have been observed and recorded from the cherts of Santa Elena, but the presence of these organisms may be accounted for by the fact that certain Radiolaria are able to exist in waters of a fairly high temperature, it is also possible that these fossils may have been abstracted from the vein walls of the country rock during the secondary process of infilling by crypto-crystalline silica.

When studying the geology of the Giants Causeway district in 1924 I noticed a strange system of well-developed joints on the surface of some basalt columns. As these only appeared on the planes of a few columns in this district, where several hundred thousand basalt columns are exposed, and as these joints were only to be found on and quite close to the surface, I firstly regarded them as a mere feature of weathering. It was only after Professor Dr. Maximilian Weber in Munich pointed out to me the striking resemblance of these joints to the photos published in Daubrée's Études synthétiques de Géologie Experimentale, and I decided to investigate this problem closer, the results of which are given as follows:–

This system of joints is only to be found at one locality in the Giants Causeway district, i.e. the lower parts (sea level) of the “Grand Causeway” (west side) opposite the “wishing chair” (the spot is marked with a white X on Fig. 1, Pl. XIV).

The fossils of the Coal Measures of South Wales have probably not been studied so systematically or for so many years as those of certain coalfields of he north of England, and it is only within recent years that any marked progress has been made in their investigation; this is especially true of the marine fossils.

In the midst of a typically graptolitic development of the Valentian Series in Wales, a thin band containing a variety of shelly fossils has recently been noticed. It occurs in the Rheidol Gorge, Cardiganshire; part of the region described by Professor O. T. Jones in 1909 (1); the locality being that referred to by him as “F. 15”, and the stratigraphical position 6 feet below the layer of calcareous nodules defining the top of the “Triangulatus-var.-band”; the shale band “2” in the table showing the beds of the zone of Monograptus communis as developed in the Rheidol Gorge (1, p.488). Professor Jones refers to the presence of “fragments of Orthoceras or Conularia” at this locality. The band has an available outcrop of about 10 feet in length, and it was possible to examine it for some 2 or 3 feet in the direction of dip. It is about 3 inches thick and is not individualized in any way other than by its fossil contents; lithologically it is to all appearances the same as the rest of the dark-blue iron-stained shales in which it occurs.

Of the more recent accounts of the Middle and Upper Chalk of Cambridge, only that of Jukes-Browne employs the definitions of zonal boundaries now usually accepted in England; for the most part, the horizons to which he refers the exposures are correct.

The mineral custerite [Ca(F,OH)]2SiO3 was first described from a limestone contact rock from Custer, Co. Idaho, the associated minerals being diopside, garnet, and magnetite. There appears to be no further record of this mineral from contact zones, though the related cuspidine [Ca(F,OH)]2SiO3 is known from Vesuvius and Franklin Furnace. In examining some metamorphosed limestones from the well-known mineral locality of Crestmore, California, the writer has found that custerite occurs in a vesuvianite rock in some abundance. As the mineral associations of this custerite are different from that of the original custerite, and owing to the very rare occurrence of this mineral, it is deemed of sufficient interest to describe this association briefly. The rock consists largely of idioblastic vesuvianite, these crystals being cemented together by a light brown base which proves to consist almost entirely of custerite, monticellite, and calcite. The custerite forms comparatively large shapeless areas enclosing subidioblastic crystals of monticellite. Under the microscope the custerite is seen to be colourless with a distinct cleavage, parallel to which lamellar twinning is developed. Sections cut perpendicular to the twin lamellae show symmetrical extinction of 6°.