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with some non-conducting medium. It was afterwards a matter of regret that the thickness of the wire had not been carefully measured by the micrometer, before,-as was doneholding it in a spirit flame. One of the observers thought he saw something come off the wire; the other did not observe this. Anyhow, after cooling, the wire behaved as the other electrode in repeating the experiment of analysing water.
There had, then, been some covering. What was it? To say that it was crystalized carbon would only be right if it could be said that the carbonic acid employed had been chemically pure. And who could say that?
Though the experiment must be called a failure, yet the acquired knowledge of what will, no doubt, always be the way of producing pure crystallized carbon by means of the electric current, was a reward for the trouble which the experiments had entailed.
LIVERPOOL GEOLOGICAL ASSOCIATION.
Field Meeting, 21st October, 1882.
The works in connection with the opening of the Edge Hill Railway Tunnel were visited, by the kind permission of Mr. HENRY A. DIBBIN, M. Inst., C.E. (Chief Engineer). On arrival at Edge Hill, the party were met by Mr. T. S. Keyte, (Assistant Engineer), and Mr. Nicholls, who conducted them through the works. The rocks exposed belong to the formation of the Pebble Beds and Lower Bunter; and, in a cutting near the University College, the Keuper Sandstone, which has been thrown down by a fault, was also observed.
6th November, 1882.
At the Ordinary Meeting held this date, at the Free Library, Mr. HENRY BRAMALL, M. Inst., C.E., President, in the Chair, the following were elected as members :—Messrs. Alexander Ross, M. Inst., C.E., James Morgan, R. E. Jones, and Frederick Padley. ·
Proposed as Members:-Messrs. Harold Kirkmann, 1, Egerton Place, Liscard, Cheshire; Benjamin Swinton Biram, B.A., Sherdley, St. Helens; J. M. Williams, The Hawthorns, Hawthorn Road, Bootle.
Abstracts Proc. Geol. Soc., Lond., March to June, 1882,-presented by Mr. G. H. Morton, F.G.S.; Green's "Physical Geology,”—presented by Mr. George Lewis; Dawson's "Chain of Life in Geological Time,”presented by Mr. W. H. Miles.
The following Communications were given
ON THE STEM OF A RECENT TREE-FERN."
BY FREDERICK P. MARRAT.
The specimen exhibited was found in a wet gully in Australia, and possessed much interest on account of its resemblance to the fossil Caulopteris of the Coal Measures.
"SOME OBSERVATIONS ON AMMONITES."
BY FREDERICK P. MARRAT.
[The following are the Secretary's Notes of Mr. Marrat's communication]
The Speaker stated that if, ten years ago, he had been asked: What was an Ammonite ? he would have readily answered that it was the shell of a cephalopodous mollusc allied to the Nautilus. The accumulated evidence regarding this animal is, however, of a very perplexing nature, as many circumstances have transpired, rendering the lines of affinity between the Nautilus of to-day, or the associated fossil spėcies of the Carboniferous, Lias, or Chalk periods, all that the geologist or zoologist could have wished them. His answer now must, therefore, be reserved. One of the principal reasons for keeping the two genera distinct is the presence in the Ammonite of an operculum, known as the trigonellites or aptychus, and other thin but doubtful organisms that have been found in various parts of the outer chamber of these cephalopods. The operculum has been found in the following Ammonites:
A. falcifer (where it is corneous or chitinous).
A. bifrons Brug., (Corneo-calcareous).
* In the Museum of Munich there are one hundred examples of Ammonites, each accompanied by its aptychus, five of which are in situ.
So many conflicting opinions regarding the animal and its operculum have arisen within the last few years that the matter is rendered doubtful. Some zoologists express the opinion that the Ammonite was an internal shell, resembling the Spirula; others assert that the animal was pelagic and floated about in mid-ocean. Others, again, have supposed that the operculum, instead of being a protection to the animal and serving as a lid to close the aperture, was an internal organ peculiar to the female Ammonite, although no analogy can be found in Nature to support such a statement. There are still some zoologists who altogether ignore the trigonellites as belonging to the Ammonite, but consider it to be the valve of a Cirriped. Mr. Sowerby thought that it resembled some of the palatal teeth of fish. Sclotheim considered it to be a bivalve, allied to the genus Tellina; and Mayer gave it as the internal shell of some undetermined mollusc. We are now tolerably well satisfied that trigonellites, or aptychus, is the opercular valve of the Ammonite.
A distinction is usually made between the Nautilus and the Ammonite in the position of the siphuncle. The speaker pointed out that the Nautili had simple sutures, but many of the subdivisions are found with slightly wavy, curved and even sinuous sutures, so that this character is by no means permanent. The situation of the siphuncle, also, cannot be strictly relied upon, as we find that it may differ in position in the young and adult state of the same species.
Another divergence was also mentioned, and one that at first sight might have had its origin in a mere accident. Thus a small stone became fix d between the whorls of a very young molluse, which had the effect of throwing the whorls out of the discoidal line, and thus would a shell of a trochiform shape be produced. Such in reality are the shells of the genus Helioceras passing into the elongated spiral of the Turrilites. In the deformed and repaired shells in the Gaskoin Cabinet, these stones, composed of quartz and granite are still remaining in the joints between the whorls of the shells.
The whole evidence is in favour of a passage from the