I am indebted to Mr. Alfred Brown, of Aliwal North, for the opportunity of describing a small fragment of a lower jaw of a Labyrinthodont which shows some unusual characters in the dentition and in the composition of the mandible (Pl. XIX, Fig. 1). Hitherto the evidence of the structure of the mandible has been imperfectly recorded in these South African reptiles.

Mr. Brown's specimen is a small transverse segment, probably from the left ramus, at some little distance behind the symphysis. This position may be indicated by an angular ridge upon the inner side, which is becoming more elevated as it extends forward. There is no suggestion of the original length of the mandible, which may have been eighteen inches. The fragment is little more than an inch and a half long. In section the jaw is subquadrate, somewhat depressed, being two inches wide and an inch and a half deep. The external surface of the bones shows no trace of sculpture. From its slightly water-worn condition the specimen (Fig. 1) was probably obtained from the reconstructed bed at the railway station at Aliwal North, which yields Theriodonts and other fossils.

The external bone is apparently vertical, traversed on the lower third by a deep longitudinal groove, in which there is a faintly marked suture. The dentary bone above the groove is slightly convex up to the alveolar margin, and shows what may be a sinuous impression above the groove. The bone below the groove, which may be infra-dentary, is well rounded on to the base.

The following note is based on two papers by Professor A. G. Nathorst and on further details which he has kindly communicated by letter. For the loan of the block (Fig. 1) thanks are due to Dr. H. Munthe, Secretary of Geologiska Föreningen i Stockholm.

By the term ‘collodion imprint’ is meant the impression of any surface on a thin film of collodion. Such an impression is obtained by letting a drop or two of collodion dissolved in ether fall on the surface to be copied. The ether evaporates rapidly, so that in two or three minutes the film is hard. If it does not of its own accord come loose at the corners, it is easily raised by a needle or sharp knife. It is then lifted on to a glass microscope-slide and preserved dry under a cover-slip held in position by gummed strips of paper or by Canada balsam. When the imprint is very sharp, the film can, if desired, be preserved in glycerine-jelly without its distinctness being greatly affected. Some films may be less successful than others, and some may curl too much, so that it is as well to take more than one imprint. In any case it is advisable to throw away the first made, since it usually retains some dust from the surface of the object, whereas following films will be free from this. If the collodion solution is too thick it may be thinned by the addition of ether or of ether and alcohol.

For many years Niagara Falls and the Great Lakes of America have been special subjects of my researches. These at last have been completed under the Commission from Dr. Robert Bell, acting Director of the Geological Survey of Canada, and later of Mr. A. P. Low, Director, with results beyond anticipation. These were obtained through precise instrumental measurements, borings, and soundings, not hitherto undertaken.

My recent survey of the crest-line (1904–5), compared with that of Professor James Hall, 1842, shows the mean rate of recession to have been 4·2 feet a year, with the average breadth of the gorge produced by the falls being 1200 feet. But a longer record (agreeing with the more recent) has been found by Mr. James Wilson and myself in discovering the position of the Falls in 1678, from the crude description and picture made by Father Hennepin at that time. Between 1890 and 1905 the rate of greater recession diminished.

I succeeded in making soundings under the Falls and throughout the Gorge by the use of Tanner-Blish self-registering tubes, depending upon the hydrostatic pressure, as the current was too strong for the use of an ordinary line. At the Whirlpool, and at some other places, it was necessary to work from a cable swung across the Gorge. Under the Falls themselves, the sounding tubes were inserted in a specially designed buoy which the force of the Fall drove down to the rocks, that had collapsed beneath the Falls themselves. These were reached at 72 feet, while the floor of the river beyond varied from 84 to 100 feet below the surface of the river.

A Small fossil with a wheel-shaped body borne on a narrow stem has long been known from the base of the Holaster planus zone in the Isle of Wight. It has been recognized as one of the Bryozoa, but has not been described, although once recorded as “near Defrancia diadema, Hag.” It has also been recorded by Dr. A. W. Rowe as “the beautiful little rotiform Bryozoon.”

The following diagnosis has been lying unpublished for eight years in the manuscript of the second volume of the Catalogue of Cretaceous Bryozoa in the British Museum. A preliminary account of the species is now issued, as the name is wanted for reference in the course of Dr. A. W. Rowe's forthcoming memoir on the Chalk of the Isle of Wight. A fuller account of the species with illustrations, on plates drawn in 1900, will be given in the Catalogue, which it is hoped will be issued during this Winter.

Blcavea Rotaformis, n.Sp.

Diagnosis.—Zoarium simple or compound, with a narrow cylindrical stem, attached in a circular concavity in the lower part of the body. The body of the zoarium is discoid, or wheel-shaped, and has on the margin a series of vertical radial projections like cog-wheels. The cogs usually project for a distance nearly equal to the radius of the disc. The cogs may be prolonged at their upper, outer corner into spike-like fasciculi. The upper surface between the bases of the fasciculi is depressed, and occupied by the small, crowded, irregular apertures of the intermediate, subordinate zoœcia.

Stone implements have long been known to occur in South Africa, but nearly all the recorded discoveries have, until quite recently, been made at the Cape. Indeed, it is only lately that the subject has attracted much attention, and that the circumstances of their occurrence have been at all fully investigated. Even now there is little precise information on the point, and yet it is essential to the solution of the problems they present. For, as one of us has previously pointed out, in attempting to ascribe to their proper source the stone implements found in South Africa, we are confronted with difficulties that are unknown in Europe. Not only has the country been inhabited down to the present day by tribes like the ‘Bushmen’ unacquainted with the working of metals, and whose origin probably long antedates the earliest Egyptian civilisation, but we find stone still employed by the Bantu for certain purposes, and in Rhodesia the question is still further complicated by the existence of numerous ruins built by an unknown race possessing a considerable degree of barbaric culture, but still employing primitive types of stone implements. Geological evidence is therefore more than usually necessary, but, when there is any, it is frequently very ambiguous owing to the characters of the superficial deposits. More often than not it is altogether lacking, the great majority of the implements found having been picked up on the surface. Colonel Feilden some time ago pointed out the probability of certain of the Zambezi implements being of vast antiquity, and one of us had already formed a similar opinion in the course of a brief visit to the Victoria Falls.

Of all the problems with which the practical geologist has to deal, none is of greater importance at the present time than the discovery of fresh sources of iron ore supply. Every inhabitant of the United Kingdom, of the United States, and of Germany requires annually about a quarter of a ton of the iron of which the world last year produced 60,000,000 tons, the result of the smelting of over 120,000,000 tons of ore. Year by year the production and consumption are increasing, and many of the deposits of the richer ores are showing signs of depletion. The question of ascertaining how the demand for the vast supplies of iron ore that will in the future be needed will be met calls, therefore, for very serious consideration, and a few statistical notes may be useful as a contribution to a discussion of the subject.