In a letter to this Magazine of May, 1895, headed “The Indentation of the Bunter Pebbles,” Mr. W. S. Gresley criticizes the summing-up of my views, given in the ‘Annals of British Geology’ (1892, p. 52), that “The indentation of the pebbles he considers to be the result of contact-solution, the water being retained at these spots by capillary attraction.” It would have been more satisfactory if Mr. Gresley could have read my original paper before penning his letter, as he would then not have assumed that I “adduce no evidence in support of the chemical theory.”

Among the fishes of the Lower Lias of Lyme Regis, Dorsetshire, described by Egerton from imperfect evidence, is the genus Osteorachis, with the single species, O. macrocephalus. The original description and figure are so unsatisfactory that nothing beyond the name of the fish is quoted even in Zittel's “Handbuch” (vol. iii, p. 230), while this bears an appended query; and the author's definition of the genus is certainly much too vague to admit of any precise determination of its systematic relationships. Under these circumstances it is of interest to return to a consideration of the fish in the light of more recently discovered specimens, which seem to the present writer to comprise not only examples of the trunk but also, at least, one satisfactory head.

In the Museum of Practical Geology there is a specimen of Ceratiocaris (No. 4435), from the vicinity of Ludlow, which was not noticed by us in the “Monograph of British Palæozoic Phyllocarida” (Palæontographical Society), 1888. It is a squeezed carapace, evidently allied to the Ceratiocaris cassioides there described and figured, pages 59–61, pl. iii, fig. 9; pl. iv, fig. 7; and pl. vii, figs. 4–6. The specimen appears to have been bivalved. The contained animal matter has caused an irregular convexity (as seen also in figs. 4–6, pl. vii above mentioned), especially in the anterior third; and here it has been broken down, leaving a small rough cavity in some obscure organic material.

In Nature of the 7th of March, Lord Kelvin reported the results of a series of experiments, which render it almost certain that Prof. J. Perry's hypothesis of the conductivity of rock increasing with the temperature is unsupported by evidence. He also stated that he had been led by later study to modify his original estimate of the age of the world, and to reduce it to about the same as estimated by Mr. Clarence King, viz. 24 million years. Thus geologists would find themselves restricted to a still shorter period for the evolution of the events of the world's history than they supposed.

The writer of these notes had hoped to have been able long ago to let the vexed questions respecting Eozoön repose in peace in so far as he was concerned, and he is now induced to offer a short summary of the evidence in the case only with the view of correcting some misapprehensions that seem to have arisen in regard to points well established, and which, independently of any question as to the nature of Eozoön, belong to the certain data of geology. These misapprehensions lead to the confounding of the structures originally discovered by Logan with things in no way related to them, and from which they had been clearly distinguished by my own original studies, and by those of Hunt, Carpenter, and Rupert Jones. New facts relating to pre-Cambrian life have also been coming to light from time to time, and many of these are connected, either directly or indirectly, with the evidence respecting Eozoön.

In recent years I have been disposed to attach more importance than formerly to the general form and macroscopical characters of Eozoön. The earlier examples studied were, for the most part, imbedded in the limestone in such a manner as to give little definite information as to external form; and at a later date, when Sir William Logan employed one of his assistants, Mr. Lowe, to quarry large specimens at Grenville and Côte St. Pierre, the attempt was made to secure the most massive blocks possible, in order to provide large slabs for showing museum specimens. More recently, when collections have been made from the eroded and crumbling surfaces of the limestone in its wider exposures, it was found that specimens of moderate size had been weathered out, and could, either naturally or by treatment with acid, be entirely separated from the matrix. Such specimens sometimes showed, either on the surfaces or on the sides of cavities and tubes penetrating the mass, a confluence of the laminæ, constituting a porous cortex or limiting structure. Specimens of this kind were figured in 1888, and I was enabled to add to the characters of the species that the original and proper form was “broadly turbinate with a depression or cavity above, and occasionally with oscula or pits penetrating the mass.” The great flattened masses thus seemed to represent confluent or overgrown individuals, often contorted by the folding of the enclosing beds.

For many years I have been deeply interested in the general history of the Brachiopoda, and I have enjoyed the acquaintance, correspondence, and friendly encouragement of most of the eminent biologists and palæontologists who have devoted themselves to the elucidation of the complex structure of this class. Here I must name with reverence Davidson, long my friend and master; Barrande, of Prague; James Hall, of Albany; William King; Eugène Deslongchamps, the Norman naturalist; Suess, of Vienna; Friele, of Bergen; Morse, of Salem; and Dall, of Washington; “all honourable men,” and many others of the fin du siècle school, whose names will be noted in the sequel.

Thanks solely to the labours of the late Oswald Heer, the fossil insect-fauna of Œningen is better known than that of any other locality or horizon in the world. But it is by no means so well known as it should be; for although Heer, in his latest enumeration of the specimens seen by him (Urwelt der Schweiz, 2e Aufl. 1879, p. 383), repeats precisely the same figures he has already given in 1861 (Recherches sur le climat du pays tert., p. 197), indicating in an interval of eighteen years no addition to his material (over 5000 specimens), his repeated additions to the number of species from that locality show that he had not fully worked over what he had. Indeed, thirty years ago, I arranged for exhibition in the Museum of Comparative Zoology at Cambridge a collection of nearly one hundred and fifty named species secured by Prof. Louis Agassiz from Heer, of which more than forty still remain undescribed; there are also a considerable number of merely nominal species enumerated by Heer in his Urwelt der Schweiz and elsewhere, duly catalogued by me in my Index to Fossil Insects (Bull. U. S. Geol. Surv. No. 71), but as yet neither described nor figured. In addition to this it may be noted that in the enumeration referred to above Heer mentions 543 species of beetles, while less than 270 nominal species have yet been published from Œningen, and only seven species from the Swiss Miocene, included in the enumeration.

The opinion that fossil Radiolarians were entirely limited to Tertiary strata prevailed until a comparatively late period. Prof. Ernst Haeckel, in his monograph on the Radiolaria, published in 1862, says “that the Radiolarians made their appearance for the first time during the Tertiary period”; and Ehrenberg, as late as 1875, defined all the Polycystina-bearing rocks as Tertiary.

The remains of fishes discovered in the Cambridge Greensand are all very fragmentary, and have not hitherto been subjected to the detailed comparison with other Cretaceous Ichthyolites which their interesting stratigraphical position renders desirable. Many specimens, however, are capable of at least generic determination, while many others are sufficiently characteristic fragments for the definition of the species. The present writer has thus been much interested during the past few years in studying collections of these fossils, and the following notes embody some of the results in reference to the ganoid fishes. The British Museum (Natural History) having recently acquired the collection made from the Cambridge Greensand by Mr. Thomas Jesson, F.G.S., nearly all the known species are now represented here; but the writer has also availed himself of the privilege of making use of the fine series in the Woodwardian Museum, Cambridge, and the Philosophical Society's Museum, York, thanks to the kindness of Professor McKenny Hughes, Mr. Henry Woods, and Mr. H. M. Platnauer. Mr. James Carter, M.R.C.S., has also kindly lent some Pycnodont jaws from his private collection

In the Geological Magazine, 1887, Professor Nicholson and Mr. Marr drew attention to a group of fossiliferous shales detected in connection with the Borrowdale Volcanic Series.

Dinas Head is a promontory 4 miles west of Padstow, jutting out into the sea from Trevose Head, and separated from it by an isthmus about 100 feet above sea-level, which is washed clear of soil by the ground seas which sweep over it from the north. The headland is 165 feet above sea-level at its highest point, and is almost as broad from north to south as it is long from east to west. The base and foreshore of the headland appear to be entirely composed of greenstone containing much calcite. The microscope shows it to be probably an altered dolerite.

The phenomena to be observed in this special rock seem to me to strikingly bear out some of the ideas and views I expressed in my former paper, when I assumed “that under such conditions, solutions of mineral constituents would be formed of great density, amounting to something like an ‘aqueous fusion’ of the substances involved, and that these solutions could solidify to amorphous and more or less indefinite compounds, or would be capable, under some conditions of cooling, of giving rise to definite minerals.”

Bearing in mind the statements made in the previous note, respecting the stratigraphical relations of the Grenville Series, and referring to the excellent account by my friend Dr. Bonney of his observations at Côte St. Pierre, and to some difficulties stated by him which merit attention, we may sum up the evidence so far, under the following statements:—

A Traveller alighting at Trontbeck station (T of Figure), at the summit level of the Keswick and Penrith Railway, finds himself standing at the north-east corner of a moorland plateau (Matterdale Common), having a mean height of over 1000 feet, and sloping gradually down to the River Glenderamackin (G), which bounds it on the north. The moorland is thickly covered with drift, and rock exposures are scarce, except here and there in the tributaries of the Glenderamackin, which run in a northerly direction from the Helvellyn Range, the principal being Troutbeck (T B) and Mosedale Beck (M B); (the latter is one of many of the same name in the district). That the stones in the drift were mainly brought from the Helvellyn Range is easily seen after a very slight examination; the boulders consist mainly of the more altered ashes and lavas derived from the Borrowdale series of the Helvellyn Range, with occasional boulders of the type of quartz-felsite dyke which penetrate the rocks of Helvellyn and its minor ridges (the best known being the familiar “Armboth and Helvellyn Dyke”); whilst the “Eycott” type of volcanic rock, occurring north of the main outcrop of Skiddaw Slates and having its nearest exposure within a mile of Troutbeck station, is entirely unrepresented. At the north-east corner of the moorland, close to Troutbeck station, a few boulders of mountain limestone indicate the point where the erratics from Helvellyn are beginning to be replaced by others brought from the eastward. The drifts of this moorland and of the region to the north have caused the interesting changes in the drainage of the area which it is the main object of this paper to describe.

Since the publication of some notes on the English Purbeckian Fishes a few months ago, the writer has been favoured by the Rev. P. B. Brodie, M.A., F.G.S., with the opportunity of re-investigating and comparing the original specimen of the small problematical fish Ceramurus macrocephalus, briefly described by Egerton from the Purbeck Beds of the Vale of Wardour. Most of the early descriptions of fossil fishes are inadequate for present needs; and no genus and species could be less satisfactorily characterized than that just referred to. A new attempt to elucidate the fossil, in the light of modern knowledge, is thus very desirable, more especially as no other specimens of the same fish have hitherto been recognized.

Leaving those local matters, there is a point of some general interest, suggested by several passages of Dr. Geikie's work, which we should like briefly to notice before laying it aside. It is in regard to those repeated depressions and re-elevations of the land which he still favours in connection with the Glacial epoch. Dr. Geikie's latest “scheme” of that epoch seems to include at least five Glacial and four inter-Glacial periods, accompanied by submergences and re-elevations to the extent of between 500 and 600 feet—the maximum being for the present restricted to that amount. Frankly, we confess ourselves unable to see the proofs for so many Glacial and inter-Glacial periods, of which, if they did occur, it would apparently be impossible—on the author's own premises as to glacial erosion—now to discover any traces. Apart from this, we might remark on the inherent improbability of such extensive oscillations of the earth's crust having happened in recent geological times, without leaving more distinct evidence of themselves than the very scanty and doubtful deposits which we have been considering.

The specimens here referred to belong to the Geological Survey of Canada, having been collected—I. some (of Quaternary age) by Mr. J. B. Tyrrell, B.Sc., F.G.S., in 1887, on the Rolling River two miles above Heart Hill in Manitoba.

The shell-structure of the Ammonoidea has received very inadequate attention from palæontologists; in most cases authors are content with describing the shell of the recent Nautilus, and saying that that of the Ammonites is exactly the same. Prof. Judd therefore suggested that I should take the subject up, when working as a research student under him. As a result, I have found that the resemblance of the Nautilus- to the Ammonite-shell is literally true; but the structure of the extinct forms throws an altogether new light on that of the recent one, while the usual homology of parts between the two requires, I think, revision.