The following notice of some fossils recently collected in the northern Malayan Province of Kedah, has been prepared at the instance of Mr. J. B. Scrivenor, M.A., F.G.S., Government Geologist of the Federated Malay States. A study of this new material has rendered necessary the revision of a published paper by the late Professor T. Rupert Jones, F.R.S., dealing with some supposed Phyllopod valves from the same country which were obtained from similarly constituted rocks as those at Kedah, although occurring at a more southern locality in the adjacent province of Perak.

The question of the supposed isostatic adjustment of the earth's crust to increase or decrease of load has recently come prominently to the fore in connexion with the Wegener hypothesis and Joly's theory of geological transgression and revolution. The principle itself is fairly well established by several independent lines of evidence, but there is room for clearer thinking as to the mechanism attending its operation. Very varied opinions are for instance held as to therapidity and completeness of the adjustment, and unjustifiable assumptions are made with regard to the displacement of magma beneath depressed areas. It is very necessary to keep an open mind on these questions and to search the available evidence for means of defining the nature of the attendant sub-crustal movements.

In 1907 Mr. E. H. Cunningham Craig's Report on the ‘Metamorphic Rocks of Trinidad’ was published, containing a general description of the structure of and the beds composing the Northern Range of the Island, and this note is accordingly intended merely to call attention to the petrographical characters of some of these altered sediments included in the Caribbian Series of Wall and Sawkins, and by far the oldest rocks in the island.

In the course of a recent study of the microscopic characters of the pyroclastic rocks of Derbyshire, a colourless, isotropic mineral, with refractive index considerably lower than that of the balsam, was noted in a thin section of a tuff from Cressbrook Dale. The rock consists essentially of a mass of lapilli containing much yellowish basaltic glass, often partially devitrified, and many felspar laths, sometimes with straight extinction, in a cement partly of calcite, and partly of amorphous, opaque material, white or grey by reflected light, which is probably decomposed volcanic detritus, of the same nature as the “toadstone-clays” of Derbyshire. Vitro-clastic structure is abundant.

The specimen to be described was disinterred by the writer in a small and practically disused Chalk pit on the east side of the road leading from Sulham village (Berkshire) in a S.S.E. direction towards Theale, and 530 yards distant from the former. The place of burial was in the undisturbed face of the pit at about 5 feet above the road level of 190 feet above sea-level. The exposure is recorded on the 6 inch map sheet XXXVI surveyed by J. H. Blake in 1895. The Chalk in which the pit occurs is coloured as “Upper”, but the precise zone is not indicated either on the map or in the memoir (1).

The question of the zinc content of the Ballachulish granodiorite (Geol. Mag., Dec, 1924, p. 554) has now been thoroughly investigated, Dr. E. G. Zies, of this laboratory, having very kindly interested himself in the matter.

Small species of Chonetes are frequently found crowding the limestones in the lower part of the Avonian Succession round Bristol and in the Mendips. Of these Ch. cf. hardrensis (Phill.) is the most persistently abundant throughout its range Km-Zl, but the two other species, Ch.failmulensis sp. nov. and Ch. stoddarti, Vaughan, here mentioned, occur in equally large numbers at particular levels within that horizon. The following notes are the outcome of the study of the material recently collected by Professor S. H. Reynolds, and myself, at St. Monica's Home of Rest, Westbury-on-Trym, but this has been considerably supplemented by specimens obtained from other localities in the district.