In almost every collection of minerals there may be found specimens of the curious little glassy balls, which, from the locality of their occurrence—the great Marekanka, near Okhotsk in Siberia—have received the name of Marekanile. These glassy balls are more or less perfectly rounded in form, they vary in their colour, through different shades of smoke-grey to orange-brown, while in size they range from the dimensions of a pea to those of a walnut. Most mineralogical treatises still continue to recognize Marekanite as a mineral, and class it either as a variety of Obsidian or of Pearlstone.

While totally disallowing the claim of Marekanite to rank as a mineral-species or even variety—the petrographer recognizes in this substance a type of rock, which proves to be by no means devoid of interest, when its properties are carefully studied, nor destitute of suggestiveness, when its mode of occurrence is thoughtfully considered.

The Carboniferous Ostracoda here described are from the deep Gayton Boring, near Northampton. Hand-specimens of the rock, obtained by H. J. Eunson, Esq., F.G.S., were given to us by R. Etheridge, Esq., F.R.S., some months ago; and Mr. Eunson kindly gave us another piece lately.

To explain the situation of the bore, as well as the position of the Carboniferous strata in it, we quote as follows from Mr. H. J. Eunson's paper “On the Palaeozoic Eocks beneath Northampton,” in the Quart. Journ. Geol. Soc. vol. xl. 1884, p. 485, etc.:

“The second trial took place near the village of Gayton, five miles south-west of Northampton, not far from the Banbury-lane crossing of the L. and N.-W. Eailway, about two miles north-west of Blisworth Station (see Ordnance Map 52 S.W.).

Of the upper dental series, Probst attempts to give a tolerably complete account, but it is only illustrated by very imperfect woodcuts. Two of the foremost awl-shaped teeth are figured by Lawley (l.c. figs. 2, 3), and the same author ascribes to the upper jaw of this species three other of the Pliocene specimens. Fig. 19 represents an anterior upper tooth from the Middle Eocene of Hampshire, and the original of Fig. 20 is another from the Miocene of Baltringen, Wurtemberg. The former (B. M., p. 4707) exhibits a short thick base with an oblique principal cone, in front of which are a number of minute denticulations; posteriorly there is only one secondary cone, pointing sharply backwards, and about half the size of the principal cone; and this is followed by another small denticle. The second specimen (B. M. 35533) has also a short thick root, and shows a somewhat similar crown; the large principal cone is followed by one small secondary and a terminal denticle, and in front there are a few coarse serrations at its base.

In order to interchange our views, and arrive at a common understanding on the question of the connection of glaciers with the formation of lakes, we undertook a joint excursion in Upper Bavaria, in the district of the Ammer Lake, Wuerm Lake, Staffel Lake, and Eieg Lake, and later, in the month of September, we visited together the shores of the Lake of Zurich, partly accompanied by Dr. K. I. V. Steenstrup, of Copenhagen, Dr. A. Wettstein and Dr. E. Brueckner, of Hamburg. We have drawn up a short protocol, both on the facts observed and of our views respecting them, which we here propose to communicate.

Professor Hull, soon after his return from Palestine, was good enough to place in my hands, for microscopic examination, a collection of twenty sections of rocks prepared from specimens obtained in the course of his expedition. Subsequently I had the advantage of receiving thirteen small specimens of the rocks from which some of the sections had been cut; and respecting these rocks some lithological notes have been published as an appendix to Prof. Hull's Memoir. At a later date I received seven other rockspecimens, representing the remaining sections in my charge; but for want of time these were laid aside unexamined until it was too late to refer to them in the published work. The object of the present notes is therefore to offer brief descriptions of these remaining rocks. At the same time I gladly seize this opportunity of correcting some errors which unfortunately crept into the previous descriptions.

In the Geological Magazine, Dec. II. Vol. II. 1875, p. 308, is a list of some English Jurassic Foraminifera, a large number of species being there noted as occurring in these rocks. We have lately received, by the friendly courtesy of the Rev. H. H. Winwood, F.G.S., and Horace B. Woodward, Esq., F.G.S., thirteen specimens of the Jurassic rocks from the south-west of England. One of these has yielded a most important series of Ostracoda. Whilst preparing a special monograph, we hasten to offer some preliminary notes on these interesting Jurassic Microzoa, at present merely noting the genera, in descending order of strata, and deferring the specific nomenclature for a subsequent opportunity.