tion yields by spontaneous evaporation olive green or yellow sixsided tables of the basic salt (Fе, 03. 2 SO2) 2(K2O. ŠO2) 6 H2O (Maus). It is also well known that ferric sulphate is easily formed by oxidation in the air of ferrous sulphate, and that this latter is frequently produced naturally from pyrites through the agency of air, light, heat, and moisture. While the oxidation of ferrous sulphate is in progress, ferric oxide is precipitated. This ferric oxide is soluble in the simultaneously produced ferric sulphate, giving rise to a series of basic ferric sulphates which are more or less insoluble, and most of which have been but little and very imperfectly studied by chemists. From what we have just stated, it is clear that, beginning with a solution of ferrous sulphate and submitting it to oxidation under varying circumstances, almost any of the possible basic ferric salts may be produced. If we begin with a lode of superficial deposit of iron pyrites, exposed to the action of air and moisture (preferably warm), and situated at such a distance from the sea and at such an altitude that the escaping drainage from the lode would have sufficient fall and sufficient distance to travel; or if it be collected into a pool or lake so as to allow its ferrous salts to be more or less perfectly converted by long exposure into ferric salts, we have all that is required to explain the formation of such a basic sulphate as that of the mineral cyprusite. It is true that, the mineral contains sulphate of alumina, but I am inclined to consider this rather as an accidental admixture. Most of the surrounding rocks are highly aluminous,* and from the fact that on the ground, at a short distance from and lower down than these deposits of cyprusite, there occur great incrustations or efflorescences, as noticed by Dr. Reinsch and myself, of soluble sulphate of alumina, one can scarcely doubt that this soluble salt is being slowly dissolved out of the cyprusite deposit, leaving behind the insoluble tribasic ferric sulphate, admixed with organic silica. The further fact that various specimens of the cyprusite, analysed by Mr. Fulton, contained varying proportions of alumina and sulphuric acid confirms this. The sulphate of alumina probably at first came there by spontaneous evaporation of the mother-liquors after the upheaval of the bed, or the drying up of the stream or deposit in which it had collected. We have therefore only to imagine at first a stream of water issuing or oozing from a pyrites lode, and carrying with it in solution the products of decomposition of the lode and its walls, *An analysis of the compact dolerite or melaphyre, often altered into wake, of this region, gives 54 90 per cent. of silica, 26 19 per cent. of alumina, and 14.53 per cent. of peroxide of iron as its composition. The percentage of alumina is higher than in any other rock of this class known to me. ferrous sulphate with aluminic sulphate. As the solution passed over the rocks, or lay exposed in situ, the ferrous sulphate would, under the actinic influence of warm sunshine, be more or less completely converted into ferric sulphate, depositing at the same time hydrated ferric oxide. This latter, acted upon by the mixed solution of ferrous and ferric sulphates, will readily form any or all of the possible basic ferric sulphates. Looking at the cyprusite from a geogenetic aspect, we must admit that depression below the level of the sea and subsequent upheaval at a later period must have taken place to explain its present situation and its contained marine organic remains. Possibly great fissures, corresponding to the position of the lodes, may have previously existed in the estuaries of streams or bottoms of small lakes or pools. These, for a long time, may have been inaccessible to the sea and to the marine polycistins (Radiolaria), and the ferrous and ferric sulphates may have been subjected to the reducing action of organic matter, restoring them to their original form, disulphide of iron, which would be deposited in the fissures. Once the fissures were so filled up, geological depressions may have admitted the sea with its living organisms, and thus entirely altered the conditions. The reducing agent being removed, the basic ferric sulphates would be deposited above the pyrites, and the polycistins, poisoned by the soluble salts of iron and alumina, would supply the existing organic silica. The fact of the cyprusite occupying only the upper portion of the deposit is attributable to the fact that alteration of the lode had only progressed to a limited extent at the time of its sub mersion. The formation contains tens of thousands of tons, and is certainly a very remarkable one in every respect. It seems unique of its kind in the world, and deserves a more complete study than I could bestow upon it in a flying mule-back visit to the Chrysophou district during the hottest and most trying period of the year, and while engaged on professional work.* * I forward a few slides of cyprusite for the cabinet of the Society, prepared for microscopical examination, as well as some slides of the insoluble residue after treatment with acids, showing the polycistins; also some of the crude material as well as some of the organic silica washed out of it, for distribution to Fellows interested in this branch of research. VI.-List of Desmidies found in gatherings made in the neighbourhood of Lake Windermere during 1883. By J. P. BISSET. (Read 9th January, 1884.) PLATE V. FIGS. 4-7. IN April last Mr. James Bisset, of Yokohama, then temporarily residing at Bowness, sent the writer squeezings from marshy ground in the following localities, viz. :-Moor near the farm of Lindeth, Bowness, and on Brantfell; also from the neighbourhood of Claife Heights and Blea Tarn. These gatherings proved rich in Desmidies, producing among other interesting forms the beautiful Micrasterias brachyptera of Lundell, not previously recorded out of Sweden and Norway. The writer subsequently visited the same district, and made gatherings at Lindeth, through Easedale, and in the neighbourhood of Angle Tarn and Low Tarn. The following list gives the forms detected in the two sets of gatherings, and bears evidence that the English Lake District is likely to be found a very prolific field for these beautiful organisms. Some particulars and figures are given of supposed new forms found in the gatherings, but which had previously been found in Scotland by the writer and his co-worker, Mr. John Roy, of Aberdeen. The following authorities are quoted for forms named, or figured, since the publication of the last English work on Desmidiex, viz. by Mr. Archer, in Pritchard's 'Infusoria.' Archer, Dublin Nat. Hist. Rev. = W. Archer, Dublin Natural History Review 1859. Archer, Dub. Mic. Club Proc. = W. Archer, Dublin Microscopical Club Proceedings, 1868. De Not. Desm. Ital. = G. De Notaris, Elementi per lo Studio delle Desmidiacee Italiche. Genova, 1867. Jacobsen, Desm, Dane. = - M. J. P. Jacobsen, Aperçu Systématique et Critique sur les Desmidiacées du Danemark. Copenhagen, 1874. Lundell, Desm. Suec. P. M. Lundell, De Desmidiaceis quæ in Suecia inventæ sunt, Observationes Criticæ. Upsaliæ, 1871. Nägeli, Gatt. einzell. Alg. = C. Nägeli, Gattungen einzelliger Algen. Zurich, 1849. Nords. Desm. Spets. = 0. Nordstedt, Desmidiaceae ex insulis Spetsbergensibus et Beeren Eiland in expeditionibus 1868 et 1870 Suecanis collectæ. Stockholm, 1872. Nords. Norges Desm. O. Nordstedt, Bidrag till Kännedomen om Sydligare Rabenh. Fl. Eur. Alg. L. Rabenhorst, Flora Europa Algarum aquæ dulcis et submarinæ, Sectio III. Lipsiæ, 1868. Reinsch, Die Algenflora = Paul Reinsch, Die Algenflora des mittleren Theiles von Franken. Nürnberg, 1867. Reinsch, Contributiones P. F. Reinsch, Contributiones ad Algologiam et Fungologiam. Lipsiæ, 1875. Wille, Fersk. Nova. Seml. = = N. Wille, Ferskvandsalger fra Novaja Semlja samlede af Dr. F. Kjellman paa Nordenskiölds Expedition 1875. Stockholm, 1879. Wille, Norges. Fersk. N. Wille, Bidrag til Kundskaben om Norges Ferskvandsalger. Christiania, 1880. Wittrock, Om Gotlands = alger. Stockholm, 1872. V. B. Wittrock, Om Gotlands och Ölands Sötvattens Lindeth, Blea Tarn, and Easedale. 13. E. sinuosum Lenorm. (E. circulare B Low Tarn. 4. C. conspersum Ralfs 5. C. Botrytis Bory. 6. C. ochthodes Nords. (Desm. Arct. p. 17, t. vi. fig. 3) 7. C. tetraophthalmum Kütz. 8. C. Logiense Bisset n.s. Brantfell and Lindeth. Brantfell, Claife Heights, and Easedale. Blea Tarn, Ambleside, Easedale, and Fig. 4. Frond shaped as figured, sometimes with a wide and very shallow 9. C. Brébissonii Menegh. 10. C. ornatum Ralfs 11. C. punctulatum Bréb. 12. C. sportella Bréb. 13. C. speciosum Lundell (Desm. Suec. p. 34, t. iii. fig. 5) 14. C. subspeciosum Nords. (Desm. Arct. p. 22, t. vi. fig. 13).. 15. C. Kjellmani Wille (Fersk. Nov. Seml. p. 42, t. xii. fig. 31) 16. C. monomazum Lundell, var. B polymazum Nords. (Norges Desm. p. 14, fig. 3) 17. C. isthmochondrum Nords. (Norges Desm. p. 12, fig. 2).. 18. C. præmorsum Breb. (Liste, p. 128).. 19. C. cœlatum Ralfs.. 20. C. Boecki Wille (Norges Fersk. p. 28, t. i. fig. 10) 21. C. crenatum Ralfs 22. C. undulatum Corda Lindeth, Claife Heights, and Easedale. Brantfell, Easedale, and Angle Tarn. Easedale and Angle Tarn. Lindeth. Ditto. Ditto. Ditto. Lindeth. 23. C. Nymannianum Grunow (in Rabenh. Fl. Eur. Alg. p. 166; Lundell, Desm. Suec. t. iii. fig. 1) 24. C. Phaseolus Bréb. 26. C. homalodermum Nords. (Desm. Aret. 27. C. pyramidatum Bréb. 28. C. pseudo-pyramidatum Lundell (Desm. Suec. p. 41, t. ii. fig. 18) 29. C. variolatum Lundell (Desm. Suec. p. 41, t. ii. fig. 19).. 30. C. granatum Bréb. 31. C. tetragonum Nägeli (Gatt. einzell. Alg. p. 119, t. vii. A, fig. 5) 32. C. pygmæum Archer Lindeth, Claife Heights, and Low Angle Tarn and Low Tarn. Common. Brantfell and Lindeth. Lindeth and Low Tarn. Angle Tarn and Low Tarn. Ditto. Ditto. Ditto. 35. C. bioculatum Bréb. 36. C. Jacobsenii Roy (C. moniliferum Jacobsen, Desm. Dane. p. 200, pl. viii. fig. 24) 37. C. connatum Bréb. 38. C. pseudo-connatum Nords. (Desm. Bras. p. 214, t. iii. fig. 17) Ditto. Brantfell and Claife Heights. Brantfell and Lindeth. |