During the last few years, in lecturing on geology at Rugby School, I have frequently given an explanation of the causes that produce contortions and faults, which I find, to my surprise, is not given in the ordinary text books, and yet seems to me an extremely obvious explanation.

I Propose now to pursue my subject by describing in some detail a series of typical examples of the principal groups of agatescent minerals; noting, as we proceed, the circumstances in each which appear to afford proper ground for future general classification.

The geology of Charnwood Forest appears to have been first systematically investigated by Professors Sedgwick, Whewell, and Airy in 1833. A very brief notice of their labours by C. Allsop, Esq., is appended to the history of Charnwood Forest by J. R. Potter, 1842, as is also a valuable and detailed memoir on the geology of the district, by J. B. Jukes, Esq.

In the “Canadian Naturalist and Geologist,” vol. iv. p. 134, figs. 8–9 (1859), I figured a small specimen of a species of Stricklandinia under the name of S. lens; but, at the same time, stated that I was not certain whether it was the true S. lens or a variety. It was more pointed in front than any of the English specimens I had seen. It had been collected in the Middle Silurian rocks on the Island of Anticosti, along with numerous other specimens, most of them in a fragmentary condition. Among these I thought that S. lirata could also be identified; and thus both of the British species have been cited in several of the publications of our Survey.

In a paper published in the Proceedings of the Royal Society of London, Dr. Duncan has figured and described six new species of Carboniferous corals, belonging to the genus Hetero-phyllia of M'Coy, from specimens found in Scottish Carboniferous limestone strata. Of these species two H. Lyelli and H. mirabilis, seem to be founded on portions, which the careful examination of better preserved specimens would have shown to belong to only one good species.

In a former number of Geological Magazine I attempted to describe the old sea-beach which extends along the coast of Llandrillo Bay, and continues round the Great Orme's Head mountain. It is my purpose now to draw attention to the series of Drift-beds, belonging to both the Post Pliocene and recent periods, which are here so well defined within a short space, and it is the more desirable to do so, because the encroachments of the sea are annually producing great changes in this district.

Having described in some detail, the rocks of the Maentwrog, Festiniog, and Dolgelly groups, and given a list of the fossils found in each, I shall now make some general remarks upon the fauna. In Part I. I have mentioned that out of all the numerous Trilobites from the Lower Cambrian rocks, only two genera, Agnostus and Conocoryphe, have been found in higher strata. Strictly speaking, this is only true of Agnostus, which passes unchanged in type from the Menevian to the Caradoc strata. On the contrary, the species of Conocoryphe from the Lower Cambrian rocks are of essentially different type from those that have been placed in that genus from higher beds. The latter have, I believe, been referred to the genus Conocoryphe rather from superficial resemblances than from true affinity.

Having lately read some interesting remarks on the well-known green-coated flints of Kent in the Geological Magazine, I am induced to offer you the following notes.

During the summer of 1864 I investigated many parts of Bulgaria, but more especially the Dobrudscha, where the sagacious observations of Capt. T. Spratt, R.N., F.R.S., frequently served me as guides. In the highly interesting Cretaceous strata at Kanara, near Küstendsche, which had been correctly identified by Capt, Spratt as Chalk, and from which Professor Reuss lately described many Foraminiferœ I discovered a pseudomorphous substance, which replaces the flint at many points along the coast, and in the Kara-Suvalley.

After referring to the scope of the subject which had been named by the Local Committee, the Author said—I will first ask your attention to the denudations, by land and sea, now taking place in the country.

The importance of the question of conformity in the classification of the earliest stratified rocks induces me to give a short description of a new section of a part of the Cambrian rocks of Llanberis, exhibiting an apparent case of unconformity towards their base.

The next group of agates which I have to describe belongs to the nested series; but is distinguished from all other varieties of that series by having a pure chalcedonic surface (unaffected, except in the form of it, by the material of its gangue); and by uniformity of colour; consisting only of white and transparent grey bands, wholly untinged by more splendid colours. But nearly all the agates of this group which now occur in the market have been dyed brown or black at Oberstein, to the complete destruction of their loveliest phenomena.

In the course of my recent investigations among the fauna of the Low Main Coal-shale in the county of Northumberland, which lies at an average depth of about 100 fathoms from the surface, I have found among numerous fish and reptilian remains three specimens of teeth that present the appearance of being vomerine in their nature. The tooth here represented in the woodcut, of the natural size resembles exactly in size and form another specimen which I have in my possession, the view exposed being the front aspect of the tooth. I have a third specimen, which exhibits the upper or attached part of the tooth; it has a sharp curved appearance, not unlike the back of a well-written letter S.

The Heudeshope beck is a small feeder of the Tees, running swiftly down a steep valley into the main stream, at Middleton Teesdale. It is wholly in the lead-measures (Carboniferous limestone), which are here nearly horizontal, undisturbed by trap, and shew only a few faults, so small as not to affect the surface. The great Teesdale fault operates on the other side of the main valley. The Heude beck flows north and south. Its source is in the table-land, forming the water-shed, between Weardale and Teesdale, whence four or five streams issue in different courses. It is unobscured by the drift beds, which characterize the opposite lower slopes of the Tees valley. It is excavated down to the solid rock, the banks have been quite undisturbed by cultivation. It passes through forty-three distinct alternations of grit, shale, and limestone, to each-of which the miners have given a distinct name; it falls about 1,000 feet in the six miles of its course, In the hope that a tramp down by side of its brawling rivulet, during the short hours of a winter day, might illustrate some theory of valley-formation, I devoted one of the last days of the year to the task.

I have in previous papers given some account of the remarkable Lower Greensand deposit at Upware, and have also described three new species of Terebratulidæ from this locality. Having obtained additional specimens of the rarer forms, and several new species, and having received many valuable suggestions from Mr. Davidson and Mr. Meyer, I propose in the present paper, first to describe some of the new species, then to make a few remarks on the numerous species of Brachiopoda which occur in this deposit, and finally to indicate their distribution in the Lower Greensand deposits of this country.

Pyrgoma cretacea, H. Woodw.—In my first Report on Fossil Crustacea (Brit. Assoc. for the Advancement of Science, 1865, Reports, p. 321), I called attention to the occurrence, in the Upper Chalk of Norwich, of a sessile Cirripede belonging to the genus Pyrgoma. This unique example—for which I proposed the name of pyrgoma cretacea—was discovered by Mr. T. G. Bayfield, of Norwich, who forwarded the specimen to the British Museum where I had the good fortune to detect its character. As no other specimen of this new species has been met with, I have thought it advisable (although only an imperfect example) to place it on record in the hope that better ones may be found. It is represented in the accompanying Plate XIV., Figs. 1 and 2, of the natural size.

Europe during the Tertiary period was invaded by successive races of animals driven from their head quarters by press of numbers or by famine, or allured by some modification of circumstances that was specially adapted for their well-being, in precisely the same way as it was subsequently invaded by successive races of men. Eocene Mammals were followed by Miocene, and those again by Pliocene, Pliocene by the Pre-glacial division of the Pleistocene, and, finally, the latter by the Post-glacial or Quaternary, in obedience to the same natural laws which compelled the Stone- to vanish away before the Bronze-folk, and the Kelt to yield to the Teuton. The parallel between the conquest of Europe by the ancient mammalia and that by man is most exact. In both cases the conquering race absorbed a greater or less proportion of the conquered. Thus the Hippopotamus major and Rhinoceros hemitæchus of the Pliocenes of Italy lingered on in France and Germany in association with, or, as it were, in a kind of helotage to, the Post-glacial fauna, just as the Kelt still survives in the midst of his Teutonic conquerors in Britain. In both there is the same uncertainty as to the ancient head-quarters of each race, except the last one, from which the present inhabitants of Western Europe are descended.

The genus Pseudoglyphea was established in 1860 by the late Dr. Albert Oppel, of Munich, for certain remains of Crustacea occurring in the Oolite and Lias formations of Bavaria, &c., previously referred to the genus Glyphea, from which, however, he has separated them on account of the difference in the direction of the furrows which mark the regions of the cephalothorax. Whether these characters will be found to be supported by others, or, to be in themselves of sufficient importance to justify the retention of the genus, must be determined by more ample materials and a better acquaintance with the entire animals belonging to both genera than we are at present able to command.

From the proposition of Professor Forbes, that a species once extinct never reappears, it follows that when a species recurs, it must have existed elsewhere during the whole of the time occupied by the deposition of the strata between the deposits containing it. In viewing the distribution of species through the cheif stages of the Lower Cretaceous system, it appears that the same species reappear when there is a recurrence of the same or similar physical conditions,—the Neocomian and Albian clays having more species in common than the intervening Aptian; and the Aptian and Cenomanian sands, being more closely allied than the intervening Albian clay. An examination of the latter, at Folkestone, appears to allow of its being divided into eleven lithological stages or beds which have been more or less recognized by all geologists and fossil collectors who have visited the district. To these beds provisional names have been assigned expressive either of their colour, position, or characteristic fossils. But in tracing all the recurring species from their genesis in one stratum to their extinction in another, these beds are found to have no great palæontological value, but to resolve themselves into two groups divided by a junction bed, in the same way as the “junction bed” separates the Albian from the Upper Aptian. Beds I. to III. forming an Upper, beds V. to X. a Lower Albian, beds IV. and XI. being the two phosphate junction beds,

Gen. I. Rastrites, Barr. (Grapt. de Boh. p. 64). Polypary simple, consisting of a slender capillary common tube, supporting a single series of isolated hydrothecæ, which are free throughout their whole length.