The Dogger of the coast from Peak to Kettleness is essentially a sideritic sandstone, and except in the Sandsend-Mulgrave district, is entirely unfossiliferous. This type of coast Dogger is well exposed at Hawsker Bottoms. To the naked eye it is a brownish sandstone of fine grain with very abundant white specks, a few small lenses of pale grey mudstone, and a very small number of bright green grains. Under the microscope it is seen to be a fairly well-graded sandstone with a few larger clastic elements, including both quartz and felspar as well as those mentioned above. The quartz grains are extraordinarily angular, doubtless due to corrosion by the matrix, and many of them are compound, i.e. microquartzites of various kinds. Felspar, mainly orthoclase and perthite, is abundant. A few flakes of chloritic chamosite and still more rare grains of typical speckled glauconite represent the green grains mentioned above. The matrix is somewhat oxidized, but still shows the usual well-formed rhombohedra of siderite, most of them with darker cores. The most notable point is that the sand grains rarely touch and are often widely spaced in the matrix, indicating simultaneous deposition of clastic elements and matrix, which is not a cement in the usual sense (Text-fig. 5). In this and in subsequent papers the term “ cement ” is used to connote that interstitial bonding material subsequently added to a bed of incoherent detrital grains which were lying in contact with each other before its infiltration : “ matrix ” is used for that interstitial material between detrital grains which are not in contact and which was therefore deposited contemporaneously with them, forming a part of the original sea floor deposit.

Four samples were sent to me by Mr. A. Farrington, two pairs collected from separate boulder clays, in each of two localities. The purpose was to investigate whether it would be possible to differentiate the two clays by their respective content of microfossils.

The sac-like structures occasionally found in association with graptolite rhabdosomes have always attracted the attention of palaeontologists whenever recognized. They have very generally been regarded as of reproductive character, though in some cases doubt has been held as to whether they were really attached to the rhabdosome; any specimens showing attachment beyond the possibility of doubt are therefore valuable, and in the case of the specimens now figured this attachment is particularly clear.

A series of Recent volcanic ashes and tuffs from various parts of Malaya has been examined on behalf of the Director of the Geological Survey, F.M.S., in order to test the reported occurrence of marine sponge spicules in certain of these deposits (cf. J. B. Scrivenor, 1930, A Recent Rhyolite-ash with Sponge-spicules and Diatoms in Malaya, Geol. Mag., lxvii, 385–393, pls. xxii, xxiii). If such an occurrence were confirmed it might be taken as evidence of very considerable changes in sea-level within recent times, since at one locality the deposits yielding the supposed spicules reach an elevation of 500 feet above M.S.L. (see Willbourn, Rep. Geol. Surv. Dept. F.M.S. for 1937 (1938), PP. 8–10).

There has been some confusion between the trilobite genera Staurocephalus and Sphaerocoryphe. This is probably due to a similarity in the bulbous character of the anterior glabellar lobe common to both genera as well as to the genus Deiphon and the Australian form Onycopyge. King (1920, pp. 532–4), in view of the character of a hypostome of Staurocephalus preserved in the British Museum and figured by Salter, was of opinion that this genus should be removed from the Cheiruridae, but hesitated to place it in the Encrinuridae. Raymond, in Eastman's Zittel (1913, p. 725), includes Staurocephalus and Sphaerocoryphe in his subfamily Deiphoninae, which he defines as Cheiruridae with a bulbous anterior lobe. His diagnosis of Staurocephalus is “Glabella with two pairs of lobes behind the bulbous portion. Cephalon with a denticulate border, and pygidium similar to that of Pliomera”. Sphaerocoryphe has only one pair of lobes behind the bulbous anterior lobe. It is necessary to consider the characteristic features of the genotypes of the two genera.

Although our present knowledge of British Guiana— particularly in detail and in the southern part of the country—is far from complete, it appears timely to attempt a synthesis of some of the major facts that are known. The following account seeks to summarize some of the more pronounced features of form and structure; it raises the question of a large discontinuity or break from south to north along the course of the greatest river—the Essequibo; it seeks to interpret the meaning of the contrasted river-systems west and east of the Essequibo; it raises the question of subsidence in the Berbice Valley, and of the early Amazon drainage; and discusses the problem of continental drift from Africa in the light of du Toit's criteria.

While studying certain Martinia-like brachiopod shells from the Permian of Iran, I have been struck by the apparent uncertainty that exists among many authors as to the relationship between the various genera represented in the Spiriferid subfamily Martiniinae of Waagen, and the following note is intended to draw attention to some of the anomalies of nomenclature and classification.