One of the most remarkablo fossils assumed to be distinctive of a particular geological horizon, and which, from its very striking outline, most readily impresses itself upon the mind, is the Rhynchonella acuta of the Lias-marlstone, a Brachiopodous shell common at Stinchcombe, Churchdown, and other localities of this district, and well known elsewhere. Having paid considerable attention to the class to which it belongs, I have long abandoned the common practice of placing in the cabinet only those specimens which chance to accord with the forms figured and described as typical. Instead of doing this, I have selected, as good examples, those which manifestly have not been crushed or injured prior to their entombment and petrifaction; and these I have arranged in series illustrative of specific development.

This mode of procedure has taught me that the species under consideration assumes forms varying from that under which it is most generally known; and it has led me to believe that several so-called species of various authors are, in reality, mere varieties of this.

All who have attentively studied the numerous Terebratulidæ of the Cotteswolds will have experienced the difficulty of assigning satisfactorily certain anomalous forms, occurring in beds ranging vertically from the Pisolite, or even lower, to the Cornbrash, to such well-established species as Terebratula maxillata, T. perovalis, T. globata, or T. intermedia, and will remember the remarkable varieties of individual character presented by other species, as, for example, T. plicata, T. simplex, T. fimbria, and T. carinata, sufficiently striking when studied in solitary examples, but, in an extensive series, not suggestive of good and stable specific differences.

There are many localities around London which possess features of interest to the geologist, that can be reached and examined on a single day. Such a one is the pretty little town of Bromley, in Kent, with a population of 4,000 souls, at a distance of ten miles from London Bridge, and now within easy reach by the Mid Kent Railway, only just opened. A mile to the north-east of Bromley is Sunderidge Park, in which is to be seen a section of the well-known oyster-conglomerato rock, in a large pit which, together with the accompanying shingle, has been quarried for various purposes for many years. This spot is noticed by Dr. Mantell in his charming volumes, as one of the most interesting localities he was acquainted with. At and around Bromley is an area of some extent, formed by the Lower London Tertiaries; a small patch of chalk, however, crops out to the east of the town, in which are some ancient quarries. One of these possesses some interest from being underground, and containing, as I was informed, several intricate windings.

The London clay, with the underlying plastic or Woolwich clays, and Tnanet sands, constitute the lower division of the Eocene strata of the Tertiary group of rocks. The London clay extends over several counties of England, constituting a large part of the soil of Essex, nearly the whole of Middlesex, and portions of Berkshire, Surrey, and Kent.

On leaving Dublin, we travelled northwards, for the purpose of examining the carboniferous rocks, and visiting the magnificent collection of fossil-fishes in the museum of the Earl of Enniskillen; we then journeyed south for Killarney and the Dingle district, but as it may be more convenient to the reader to travel geologically, we will reverse the order of our journey, and visit the Upper Silurian and Old Red Sandstone districts before we examine the carboniferous deposits.

The lower Cambrian rocks of Wales, of which the Oldhamia-schists of Ireland are believed to be the equivalents, pass upwards by insensible gradations into the Lingula-flags, to which they are altogether conformable. The Lingula-flags are reckoned to be four or five thousand feet thick, and the Llandeilo or Builth-beds, which cover up these, are probably as thick; but geologists are, as yet, uncertain whether they possess in Ireland any true equivalents either of the Lingula-flags or of the Llandeilo and Builth deposits. There are, however, fossiliferous rocks of the Bala and Caradoc age in Ireland similar to those which, in Wales, succeed conformably to the Llandeilo and Builth beds, and they may be examined at Courtown, in the county of Wicklow, and again at Tramore, south of Waterford. They are unconformable to the rocks below, which are undoubtedly Cambrian, and thence, we imagine, has arisen the suspicion that the Lingula-beds and Llandeilo-flags have never been deposited in Ireland, or that if they were, they have been denuded and swept away before the deposition of the Bala or Caradoc strata.

After the al fresco dinner of the “Worcestershire Naturalist Club,” under the Sorb Tree, in Wyre Forest, I and Mr. Baxter of Worcester, well known for his botanical acumen, started for the Ludlow promontory, via Cleobury and Caynham. I copy from my note-book the following geological facts—some may be of use to the definer of the limits of ancient life-periods; others, deficient in value for such purposes, may save future explorers time and trouble in working up the district.

I arrange them in the order of their occurrence.

The “Brownstones” of the cornstone series are finely quarried a mile east of Cleobury; very fine rippled-marked slabs may be obtained, and ichnites (fossil footprints) should be apparent, it being an equivalent bed to the one in which they occur at Puddlestone, Herefordshire.

The curious outlier of the “Forest Coal-field,” on which Cleobury stands, has been fruitlessly sunk into for coal this year; another proof that the geologist is not “abroad” in the land, no bed in the whole coal-field having paid expenses, and, in some instances—this I find among the number—the Old Red has been reached without coal being met with.

The south end of the Titterstone Hill, presenting a fine escarpment of mountain limestone to the valley, is very barren of fossils. I could not meet with or hear of any of those interesting fish-jaws, spines, and palatal teeth, so numerous along its northern sides at Oreton and Farlow.