The nature and arrangement of the “gills” of Eurypterids is not known in detail. A specimen of Slimonia in the Sedgwick Museum (No. A16237a), figured by Laurie (1893, pl. 1, figs. 5, 6, p. 514), seems to show their structure and segmental arrangement better than any described elsewhere. Owing to the rather poor quality of Laurie's figure and to the important conclusions which follow a study of this specimen, it has been thought fit to re-describe it here.

This paper is an attempt to review briefly the progress of geological research in an area familiar to zoologists as the classic ground covered by Alfred Russel Wallace, but which is also the field where Dutch geologists have for many years been carrying out valuable work on a much larger scale than has been possible in the smaller areas under British control in the Malay Peninsula and Borneo. There is a considerable amount of geological literature dealing with the Peninsula and Archipelago. In The Geology of Malaya (1931) is a bibliography of that concerning the Malay Peninsula, and in F. H. Hatch's translation of Posewitz's Borneo (1892) will be found lists of the earlier literature dealing with both the British and Dutch portions of that island. In the Malay Peninsula the Journal of the Straits Branch of the Royal Asiatic Society has included scientific papers since the appearance of their first number in 1878; and in 1927 C. E. Wurtzburg produced an index, including an earlier index by W. D. Barnes, of the Journal up to 1915, when the title of the society was changed to The Malayan Branch of the Royal Asiatic Society. In 1930 the Malayan Branch published an exceptionally interesting number containing a translation by H. V. Mills of Manoel Godinho de Eredia's Description of Malacca, Meridional India and Cathay, originally written about 1600 in Portuguese. This is the earliest known publication that can be called scientific about this part of Asia and contains information about tin and gold, also “traces of diamonds and emeralds as Pliny points out” which later workers have not been able to find.

Certain of the Lower Carboniferous algae are preserved as moulds in a fine-grained calcareous matrix precipitated by their own life processes. The cell walls of the alga are not preserved. This observation applies to the genera Ortonella, Mitcheldeania, Bevocastria, and Girvanella. In the case of Mitcheldeania the filaments are so close together and so parallel that an impression of a definite wall may be obtained, but occasional irregularities and a comparison of the microstructure with that of other forms leaves no doubt that this too is a precipitate.

The younger rocks of Iceland (Pliocene to Present Day) occupy the broad median zone shown in Text-fig. I; the boundaries are only approximate in places, and information is lacking with regard to the eastern one particularly. Outside this zone early Tertiary basalts predominate but (I) the uppermost basalts are regarded by some authors as Quaternary, (2) Quaternary and Recent volcanic rocks occur in the Snaefells Peninsula and in Skagi. The thickness of the early Tertiary series has been estimated at 3,000 m.; it may well be more, and it is reasonable to suppose that originally these basalts extended over the site of the median zone. Hitherto all workers in Icelandic geology have considered the zone to be a graben where the older rocks have been faulted or tilted downwards, but recently R. A. Sonder (1, 2) has put forward the startling idea that it is a horst, a view which is discussed, and not unfavourably, by H. G. Backlund (3). Before considering this new conception attention will be drawn to evidence in the neighbourhood of the north-western boundary of the zone, evidence which is not mentioned by Sonder and which, although it has been known for over 70 years, is often ignored or forgotten by writers on Icelandic tectonics.

Eight inliers of Carboniferous Limestone are situated between Ashby de la Zouch and Melbourne on the northeastern side of the Leicestershire Coalfield. They may conveniently be divided into a western group consisting of the Ticknall, Calke, and Dimminsdale exposures, all of which occupy comparatively low ground in valleys, and an easterly group, Breedon Hill, Breedon Cloud, Barrow Hill, Osgathorpe, and Grace Dieu. The first three of the latter group form prominent hills rising above the Triassic rocks which surround them. They are also remarkable for the high dips in the rocks composing them. In the other inliers dips of less than 15° are the rule, while dips of about 5° are common.

As a result of recent work on the correlation of the Coal Measures in the various British coalfields it is now possible to determine the relative ages of the chief productive measures in the different areas. Some aspects of this work were summarized in 1933 but much further work has been done since that time, especially with reference to the Scottish coalfields (Weir and Leitch, 1936). The results of these investigations may be expected to throw considerable light on the physiography and other factors controlling the deposition of the Upper Carboniferous rocks, but in the present note attention is drawn only to the zonal distribution of the more important coals in various British coalfields.

The Cretaceous System of England, according to A. J. Jukes-Browne1 is “naturally divisible into two distinct and different series of strata”, namely a lower series consisting chiefly of sands and clays, and an upper series, consisting mainly of chalk. The succession on the whole is easy to unravel, and was correctly described (even before the name Cretaceous had been thought of) by Webster in his Letters, written in 1811 and published in 1816 in Sir Henry Englefield's Isle of Wight; it is almost exactly the same as we recognize it to-day. Two slight changes have been made, but they have been considered by some to be changes for the worse. Firstly, the beds to which the name“Greensand” had originally been applied by Smith and Webster2 are now called “Upper” Greensand, a term that has given rise to much confusion3; and, secondly, the “Ferruginous Sands” are now known as “Lower” Greensand, a name that was strongly condemned by workers like Fitton, Godwin-Austen, and Judd. It is on record4 that even Jukes-Browne admitted that he had long been endeavouring to do away with the awkward and misleading terms “Upper” and “Lower” Greensand ; but these names, though better not used without locality, have now become too familiar and are too useful for mapping to be abandoned entirely in favour of the more precise stage names Cenomanian, Albian, and Aptian.

Recently I have had the opportunity of working through a large collection of Lower Carboniferous fossils, of which there appears to be no record in geological literature. The collection was made by R. H. Tiddeman from the district between Pateley Bridge and Settle, and is now in the care of the Skipton Museum. The bulk of the collection was probably made between 1890 and 1900 and has hardly been touched since.

In an article on “Limestone and the Origin of Feldspathoidal Rocks”, which appeared in the Geological Magazine ten years ago, I referred to the malignite of Poohbah Lake, Western Ontario, and was so bold as to predict that “further work at Poohbah Lake … will eventually furnish evidence of the presence of limestone in contact with the alkaline eruptives”,1 In August, 1939, I found myself at last in a position to visit the locality and see how far my prediction could be verified.