the fronds of the fenestrated species should be found, in almost every instance, with the celluliferous face adherent to the stone in which they are embedded. The reason for the fronds being so persistently adherent by this face, is that the pores on the celluliferous face have often raised margins, and are more or less slightly projecting beyond the surface of the frond, giving it a rougher aspect, while the non-celluliferous face is comparatively smooth, being only faintly striated or granulated in most instances. This smoother face is consequently much less adherent to the matrix than the celluliferous face, and is therefore that which is most constantly exposed. In some of the harder limestone shales, such as those of Hairmyres, East Kilbride, and of the Beith and Dalry districts in Ayrshire, we sometimes find the fronds of the Polyzoa showing the celluliferous face, but this is owing to the circumstance that there the fronds have been fixed down by one or other face upon a layer of harder shale or limestone, and have been covered by a layer of softer shale, so that when the rock comes to be split up, the parting is in the line of the soft shale; so those specimens that chance to have their celluliferous faces next to the soft layer are now and again exposed. On the other hand, where the Polyzoa are embedded in soft shales that yield readily to the influence of the weather, like those of Dikehead, High Blantyre, or Gillfoot, Carluke, the tendency in them is for the celluliferous face to adhere to the matrix. However beautiful fronds of Polyzoa showing only the reverse face may be, they are much more beautiful, and become more valuable to palaeontologists as specimens, when the celluliferous face can be examined, for it is only by the number and form of the cells in the fenestrules that the several species belonging to the various fenestrated genera can be correctly determined. Recently Dr Rankin of Carluke, when examining the Polyzoa of the Gillfoot shale, was led to try the experiment of fixing small portions of the fronds of Polyzoa by their non-celluliferous face to a bit of melted black sealing-wax, which adhered firmly to the frond. On the shale being placed in water, the wax brought away the bit of Polyzoa with its celluliferous face exposed, which on being cleaned, by washing with a brush in water, allowed the cells to be clearly examined. To Dr Rankin, therefore, am I indebted for the hint that first led me to try the same experiment on large fronds of Polyzoa, but using instead of the black sealing-wax, a melted layer of common asphalt, free from sand, such as is used for street pavements. By this method, as you will see from the series of specimens exhibited, I have been successful, beyond my expectation, in transferring to the layer of melted asphalt the largest fronds of Polyzoa preserved in our shales, in all their entirety, and showing the celluliferous face in a manner which is hardly excelled in recent specimens. The method adopted may be briefly explained as follows:After selecting the specimens,-it being only those preserved in soft shales that can be successfully treated by the asphalt process, as those fronds embedded in hard shale or limestone cannot be lifted by this method,-let them be well dried at the fire, or in the sun's rays, to free them from moisture; and before applying the layer of asphalt, heat the specimens at the fire, this making the asphalt adhere much more firmly than when they are cold and damp. The asphalt may be melted and spread over the face of the frond by a piece of iron, or a kitchen poker, heated nearly to redness, having at the same time a bit of tough brown paper lying ready to cover the layer of asphalt while it is still warm. The paper must be pressed on the asphalt with the fingers, and spread smoothly over the surface; and in order that the frond may adhere firmly to the asphalt, see that no gum or other mucilage is allowed to touch the specimen. The layer of paper strengthens the asphalt, and forms a better surface for afterwards fixing the specimens to the tablets on which they are mounted. For large fronds of Polyzoa, it is better to use two or three alternate layers of asphalt and paper; which make a thin firm cake, not liable to break or crack across when being cleaned. Having applied the asphalt, place the shale in water, letting it lie for a time. Some shales part from the fronds of the Polyzoa in a few minutes, while others will take an hour or two, or even a day; the process may be hastened, however, by placing the shale in a saucer filled with water, and as it softens, picking it away with the point of a knife, until the face of the frond appears. Then wash the face of the frond in clean water, until the whole of the cell-pores appear quite clean, using a hard nail-brush or tooth-brush for the purpose. If the frond has been well fixed to the asphalt, it may be washed without fear of its removal. When the frond is properly cleaned, the surplus asphalt and paper can be cut away from around it by a pair VOL. III. of sharp scissors; and when this is done, the specimen may be considered finished. The fronds of the Polyzoa being generally of a greyish-white colour, they contrast very favourably with the black ground of the asphalt; and the manner in which the surface of the celluliferous faces of the fronds can be examined over their whole extent, renders this method of treating them very satisfactory. The genera from our soft shales that I have had an opportunity of operating upon, are the several species of Fenestella, Actinostoma, Synocladia, and Glauconome, and these have all turned out well. I have also used this method for exposing the outer surface of some of the Aviculopectens, and other shells which were adherent by their rough faces to the stone, and I find it answers very well. Before the discovery of treating the larger fronds of the Polyzoa by the asphalt process, when we wanted to examine the celluliferous faces of the various species, we were content with the fragments of the broken up fronds from the soft weathered shales. When these fragments were collected, they were found to be often coated by a thin layer of clay. In order to remove this, I have adopted the following plan :-I pick out of the shale all the fragments to be examined; I then take a glass slide, and coat it with a layer of thin gum; next, with the forceps, lifting the fragments of the Polyzoa and placing them on the gum, with the celluliferous face uppermost. When this is finished, I allow the gum on the slide to dry slowly for a day or two, until it is quite hard; I then place the slide in a saucer filled with water, brushing the specimens gently and quickly with a tooth-brush until they are quite clean, the gum holding the specimens securely, while the washing improves the appearance of the cells. The slide may then be left in the water until the fragments are melted off, when they can be easily collected with a soft hair pencil, and dried on blotting paper, after which they are ready for mounting on slides for microscopic examination. I have found this to be a good method for cleaning fragments of Polyzoa only to be had as weathered specimens in the shales, and they form beautiful and interesting cabinet objects for microscopic investigation. Natural History Society of Glasgow. SESSION 1876-77. President Professor JOHN YOUNG, M.D., F.G.S., F.R.S.E., Glasgow University. Vice-Presidents JAMES RAMSAY, 159 Eglinton Street. THOMAS CHAPMAN, 56 Buchanan Street. 1851 HUGH COLQUHOUN, M.D., Anchorage, Bothwell. 1851 WILLIAM FERGUSON, F.L.S., F.G.S., &c., of Kinmundy, Aberdeen shire. 1856 ROBERT HISLOP, Blair Lodge, Polmont. 1866 Dr. W. P. SCHIMPER, Professor of Geology, University of Strasbourg. CORRESPONDING. 1851 Robert Gray, F.R.S.E., 13 Inverleith Row, Edinburgh. 1852 T. B. Grierson, M.D., Thornhill, Dumfriesshire. 1861 John Shaw, Ph.D., Principal of the Gymnasium, Colesbur, South Africa. 1863 Rev. James Dewar, Arrochar. 1863 Rev. H. W. Crosskey, F.G.S., Birmingham. 1863 Edward R. Alston, F.Z.S., F.L.S., F.G.S., Arts Club, Hanover Square, London. 1866 Right Hon. The Earl of Haddington, Tyninghame, Prestonkirk. 1866 James A. Mahony, Ramelton, Donegal, Ireland. 1866 Robert Macdowal, Surgeon, Panama Steam Navigation Company, Panama. 1866 Rev. James E. Somerville, B.D., Broughty-Ferry. 1867 Thomas Edward, A.L.S., Banff. 1867 John Buchanan, of the Government Survey, Wellington, N.Z. 1867 Thomas Anderson, Girvan. 1867 George Thomson, Victoria, Africa. 1868 Rev. Dr. Gloag, Galashiels. 1869 George S. Brady, C.M.Z.S., Sunderland. 1869 Capt. H. W. Feilden, C.M.Z.S., Junior United Service Club, London. 1869 Rev. John Ferguson, New Pitsligo. 1870 James Hardy, Old Cambus, Berwickshire. 1871 Alexander Gray, Chartered Bank of India, Batavia. 1871 Edwin Lees, F.L.S., F.G.S., Greenhill Summit, Worcester. 1873 Sir George Hector Leith, Bart., Ross Priory, Dumbartonshire. 1875 Robert Hill, Berbice, British Guiana. 1876 William Hamilton, Yokohama, Japan. 1877 H. B. Bailey, Newton, Mass., U.S. ORDINARY. Those marked * are Life Members. 1872 Aitken, David, 14 Robertson Street. 1863 Alexander, John, Menstriebank, Dowanhill Gardens. 1868 Angus, William Craibe, 159 Queen Street. 1872 Arrol, Archibald T., Millgrove House, Alloa. 1862 Bain, James, F.R.S.E., 3 Park Terrace. 1863 Balloch, Robert, 88 Union Street. 1876 Barclay, Thomas, 121 West Regent Street. 1875 Baxter, William, 16 Gibson Street, Hillhead. 1869 Bennett, Robert J., 50 Gordon Street. |