Shortly after my arrival in Cairo, Dr. Schweinfurth, of that city, was so kind as to conduct me to a remarkable sea-terrace at the foot of the Mokattam hill, behind the tombs of the Caliphs, and stated, on the authority of Col. Ardagb, R.E., to be at an elevation of about 200 feet above the level of the sea, and which, I believe, was first described by Oscar Fraas. At this place a cliff of hard Eocene limestone, about 30 feet in height, has been perforated by Lithodomi, whose burrows are now filled with a grey calcareous deposit, and valves of a small species of oyster are also attached to the surface of the rock. The burrows resemble those of an ordinary Mediterranean species of Lithodomus, but I did not see the shells. The oyster has been described by Fuchs as a new species, under the name O. pseudo-cucullata; but, according to Dr. Schweinfurth, it does not seem distinguishable, except as a variety, from O. cucullata, Born. (=O. Forskali, Chemn.), of the Red Sea. Since the locality was observed by Fraas, Dr. Schweinfurth has discovered other shells in the crevices of the rock, more especially a Pecten, a Terebratula, and a Balanus, all modern species. The recent character of these shells and their mode of occurrence and state of preservation, oblige us, I think, to assign them to the Pleistocene, or at farthest the later Pliocene period, though I am aware that they have been regarded as Miocene.

Several trochiform shells found in the Jurassic rocks, which were formerly referred either to Trochus or to Solarium, have in more recent years been regarded as related to the genus Onustus. I am not aware who was the first author to adopt this view, but we find Hébert and Deslongchamps (1860) recognizing the genus in the Callovian of Montrueil Bellay. Subsequently Lycett (Suppl. to the Great Ool. Moll. p. 103) gave a diagnosis, more especially as applicable to the Jurassic species, and described Onustus Burtonensis from the Forest Marble of Burton Bradstock.

Of the abounding Trilobites which mark the faunas of the Lower and Middle Palæozoic rocks few survive into the Upper Palæozoic. Three genera, if indeed they really deserve that name, have been described from the Carboniferous beds in England—Phillipsia, Griffithides and Brachymetopus. Only the first of these is yet known to occur in American Palæozoic strata. But on the other hand two species of Proetus have been announced from America—a genus not yet recognized in England. It is true that the distinctions are so slight that possibly these last might be as correctly referred to Phillipsia as to Proetus.

The several species of Eryon, described by various authors, appear to be distinguishable as separate genera, which are as definable from one another as from the recent forms of Polycheles and Willemœsia; but the variability appears not to be greater than in those that are separated in time through geological æons, than in those that are contemporaneous in geographical space.

The origin of metalliferous deposits has long been a subject of discussion. Professor Joseph Le Conte, however, seems to have arrived at a very decided opinion on this question, for in a contribution to the “American Journal of Science” (3rd series, xxvi. p. 1—19, July, 1883), after referring to Sulphur Banks and Steamboat Springs in California, he says: “Thus then subterranean waters of any kind, but especially alkaline, at any temperature, but mostly hot, circulating in any direction, but mainly upcoming, and in any kind of waterway, but mainly in open fissures, by deposit, form metalliferous veins.”

The true test of the classification adopted for European sedimentary formations is to endeavour to apply it in distant parts of the earth. It will then be seen whether the classification in question is real, or whether it is founded on local and accidental peculiarities of the rocks in a particular region.

At the present stage of the controversy, it may seem, to those who have read carefully the paper of M. Marcou in the March Number of this Magazine, that very little remains to be said. Yet, however much it is to be regretted, it must be feared that insular prejudice still finds place with English geologists, and prevents them from seeing so clearly as they otherwise might do the full bearing of the evidence which we possess. I have thought, therefore, that at the present juncture it would be useful if one gave a short historical résumé of a few facts, taken partly from the introduction to Geinitz's great Monograph on the Dyas. The title of this work is of importance as an index of the stage at which the battle between the followers of Murchison in this country and the advocates of what we may call German views had arrived in the year 1862, when Geinitz's great work was published in Leipzig. Some years before this, Murchison had propounded his view of a “Palæozoic Trias” in his Siluria, and subsequently he went over a good portion of Central Germany with Prof. Morris, and on his return gave to the Geological Society his long paper on the Thüringen and Hartz country.