The hydraulic limestone series which cap the Silurian rocks of the New York sections, and are commonly embraced under the name “Salina Group”, are probably the richest known depository of remains of the Merostome Crustacea. During the past fifteen years we have been engaged upon the study of this fauna, and the results at which we arrived in our memoir on the Eurypterida of New York could not have been safely attained without the previous labours of Dr. Woodward and the late Professor Rupert Jones, of Huxley, and Hugh Miller for the British species; of Friedrich Schmidt, Nieszkowski, and Holm for the species of the Baltic basin.

The “Isle” of Purbeek includes part of a heathy tract underlain by the Tertiary beds of the Hampshire Basin, a central ridge formed by the Chalk which rises abruptly from beneath those beds, and, in its southern part, a hilly region underlain by Wealden, Purbeck, Portland, and Kimmeridge strata, and terminated by bold cliffs. Each formation gives rise to characteristic features in the landscape, the Portland Stone especially forming a dominant escarpment and vertical sea-cliffs.

It will be recalled that to the list of theories relating to the origin of flint Liesegang has added another, namely, that the flint is due to the rhythmic precipitation of a silica solution diffusing through the Chalk. Cole in an admirable essay has made this view accessible to English readers, and at the same time somewhat expanded the original suggestion. Yet little by way of evidence is offered beyond a certain plausibility in the idea, and its undoubted competence to explain better than any other hypothesis yet suggested the remarkably regular recurrence of flint lines. When reading over the chief Cretaceous literature with this problem in mind, there seemed to me to be a not inconsiderable body of fact lending support to this view. Accordingly the object of this paper is to examine existing data in the light of Liesegang's suggestion in order to see whether or not it may be regarded as a reasonable working hypothesis.

The Dartmouth Slates of South Devon and Cornwall, which correspond, it would seem, to the Schistes d'Oignies of the Ardennes, are not seen in North Devon, but may be concealed by later rocks and be represented in South Wales and the Welsh Border by the Red Marls of the Lower Old Red Sandstone. It is possible that the Foreland Grits are a local facies of the upper portion of the Dartmouth Slates, just as the arenaceous Cosheston Group is a local development of the upper part of the Red Marls. Both the Foreland Grits and the Cosheston Group appear to have yielded the typical Old Red Sandstone plant Psilophyton.

Since no undoubted fossil remains of this group of hydroids have been previously recorded, with the exception of possible forms indicated by Ruedemann but placed by him with the Graptolites, it is thought that a few brief notes on a recent discovery in Victoria may be acceptable to readers of this Magazine. A description of the fossils by one of us (F. C.) will appear in the Proc. Roy. Soc. Victoria, while a description of the stratigraphy of the area will be given by the other author (E. W. S.)

Another direction in which the work of the Survey could with advantage be extended is in the execution of deep borings on carefully thought-out schemes by which a maximum of information could be obtained. Both in Holland and Germany borings have been carried out to discover the nature of the older rocks beneath the Secondary and Tertiary strata, and Professor Watts, in his Presidental Address to the Geological Society in 1912 (Proc. Geol. Soc., pp. lxxx–xc), has dwelt on the importance of exploring systematically the region beneath the wide spread of the younger rocks that covers such a great extent of the East and South of England. Professor Boulton, my predecessor in this Chair, has endorsed this appeal, but nothing has been done or is apparently likely to be done in this direction. It seems extraordinary that no co-ordinated effort should have been made to ascertain the character and potentiality of this almost unknown land that lies close beneath our feet and is the continuation of the older rocks of the west and north to which we owe so much of our mineral wealth. It is true that borings have been put down by private enterprise, but, being directed only by the hope of private gain and by rival interests, they have been carried out on no settled plan, and the results and sometimes the very existence of the borings have been kept secret. The natural consequences of this procedure have been the maximum of expense and the minimum of useful information.