Gen. Char.—Corallum composite, with an epithecate base, the corallites subpolygonal, and indissolubly united by the coalescence of their walls. The corallites are sometimes circumscribed, but they are for the most part more or less extensively connected by deficiency of their walls in particular directions, so as to give rise to sinuous rows of serially-united tubes. The calices, like the corallites, may be circumscribed, but are mostly in the form of vermiculate grooves sorresponding with the serially confluent corallites. The calices ire not oblique, nor are the corallites reclined. Mural pores are numerous and well developed. Septa and septal spines are wholly wanting. The tabulaæ are numerous, being simple and complete in the circumscribed corallites, but becoming vesicular in the rows of serially confluent corallites. New corallites are produced by fission.

In any inquiry into the history of the earth as a whole, we are met at the outset by a serious difficulty. In human affairs a general view of history, not confined to a single country, would be practically impossible, were we ignorant of the relations of the various eras from which different races reckon their dates: thus, it would be impossible to write a connected account of the history of Europe in the classical period were it not possible to determine the relation of the Olympian era to that dating from the foundation of the city of Eome. Yet the supposed case is not unlike that to which the geologist addresses himself when he endeavours to make a connected survey of such widely-separated regions as Europe, India, Australia, and America.

In the supposed case of the Greek and Roman eras, there are numerous points of contact, principally dates of battles, which, having been recorded by both nations according to their own system, enable us to compare the two, and so to determine what would be the date of any event, recorded by the one, had it been recorded by the other. But in geology we have no such points of contact; there is a very general tendency to regard any two series of beds, in which a few fossil forms specifically identical are found, as of contemporaneous origin. That this view is erroneous, and that it would be nearer the truth to say that two widely-separated beds, in which the same forms are found, could not be of contemporaneous origin, was long ago pointed out by Forbes and Huxley, the word homotaxis being invented by the latter to express the relation existing.

In my last essay I had occasion to refer to the former existence of icebergs in localities which now lie in latitudes lower than those in which glacial action is known to have reached, even during the last Glacial period. But, surprising as it may be to find evidence of glacial action within a few degrees of, and, as in the case of the Eowen Eiver Coal-field, a few degrees within, the tropics, this sinks into insignificance in the face of the evidences of repeated Glacial periods that may be found in India, and especially in the Himalayas.

The writer has for some time hesitated to seek in the pages of the Geological Magazine a publication of his-experiences upon the above subject. He fell last year into a grievous mistake with regard to it, and suffered that mistake to be published in the “Transactions of the Devonshire Association for the Promotion of Science, Literature, and Art.” It will be his duty, when the opportunity comes round (as shortly it will), to call attention to that mistake in the pages of the same periodical. In the meantime he thinks that the subject, and even the mistake associated with it, may be of something more than local interest. At least the recantation of a published error cannot be too widely circulated.

Much confusion and difference of opinion appears to exist with regard to the classification and nomenclature of the strata which form the lower part of the Cretaceous system, and the chief element of this uncertainty and confusion is the misconception which prevails respecting the proper signification and application of the term Neocomian. The object of the present paper is to explain the continental usage of this name, and by showing its inapplicability to any of our English strata, to prepare the way for a more satisfactory grouping of our Cretaceous rocks.

For many years English geologists were content with the nomenclature employed by the earlier students of the Cretaceous system— Webster, Murchison, Mantell and Fitton. In 1864, however, the French term Neocomian was introduced by Prof. Judd, who adopted it for the Cretaceous portion of the Speeton Clay, and Sir Charles Lyell subsequently used it as a synonym for the whole Lower Cretaceous series in England as distinct from the Upper Cretaceous series or the beds lying above the Lower Greensand.

In the Geological Magazine for December, 1882, I published a brief note upon the “Discovery of Cambrian Rocks in the Neighbourhood of Birmingham,” in which evidences were adduced demonstrative of the fact that the oldest sedimentary strata of the Lickey Hills, and of the neighbourhood of the town of Nuneaton, previously referred to the Llandovery and Carboniferous respectively, are, in reality, of Cambrian age. Since that date these Cambrian areas have been in part mapped by the members of the Field Geology Class of the Mason College, and many confirmatory and interesting points of detail have been detected by myself and others. Some of these will be found incorporated in Mr. Jerome Harrison's valuable paper on the “Pre-Carboniferous Floor of the Midlands,” published in the Midland Naturalist for 1885. My friend Mr. T. H. Waller, B.Sc, kindly undertook the microscopical examination of the igDeous rooks associated with these Cambrian strata, but the results of his observations are as yet unpublished.

The relations of the various rocks of the district lying to the North and South of Nuneaton have already been discussed by Prof. Lapworth from the data afforded by investigation in the field. He put into my hands many specimens of the different rocks for the purpose of microscopical examination. I have also received specimens from Mr. W. J. Harrison, and have collected some myself. Mr. J. J. H. Teall has also placed at my disposal a number of slides which he has had prepared from material of his own collecting.