Hitherto very little of the chica, I presume, has reached Europe; and very few experiments have been tried for the solution and application of the colouring principle. I feel strongly prepossessed, however, that the carucru might be applied to useful purposes in dyeing, but I can say nothing positive on this point, having made no experiments with it as a dye,—nor having discovered its chemical properties any farther than above mentioned. It would be extremely interesting, by proper chemical agents, to find a solvent which should not injure the colour, and also a method of applying it either with or without a mordant—with a view to employ it like indigo as a dye, as well as a pig ment. It is certain that it might be abundantly procured by planting and manufacturing it in Guiana, where the specimens I have alluded to prove the soil to be most congenial to its growth, or by sending it up the Essequibo. In the mean time, the finest quality may be had of the Taruma Indians. The chica is not merely esteemed as a pigment, but is considered in the Orinooko as the most sovereign remedy for erysipelas, where that complaint is very prevalent. I never, indeed, witnessed its use myself; but, from the strong terms in which I have heard many people speak of its efficacy in their own cases and those of others, I cannot but consider it as a remedy well established, and worthy of further attention. It is simply made with water into a paste, thinly spread on old linen or cotton, and applied as a plaster, so as to entirely cover the inflamed part. They say that one application is sufficient, unless the disease be far advanced. I have also heard it mentioned as an internal remedy, but in what case or what complaint I do not now remember. Report on the Impression made on the Ground by the Foot of the Sow. By Messrs ROBERT SPITTAL and ROBERT STEVENSON junior. In compliance with a wish expressed at the last meeting of the Wernerian Society, that the question as to the impression made on the ground by the foot of the sow, in relation to Dr FlemJULY-OCTOBER 1829. U ing's remarks on that subject, be decided by experiment, I beg to lay the following remarks, containing the conclusions which my friend Mr Robert Stevenson junior, and I, from experiment and observation, have come to on this topic. The common domestic pig was the subject of our observations. To ascertain the impression made by the feet of these animals, we with some difficulty caused them to walk across a board spread over with soft clay, to about three-eighths of an inch in thickness, and were satisfied, on subsequent examination of the marks made, that, at some places, these were bisulcated, but at others, they presented, besides the bisulcated impression, those of the two posterior toes; and indeed, this was the most frequent appearance. The board, in this case, was placed in a horizontal position, and we could not, owing to the unruly nature of the animals, succeed in making them walk along it while in the position of an inclined plane; but, what answered nearly the same purpose, the animals were let out into a court, the surface of which was generally uneven, hard at some places, and soft at others. In this case, we observed, that while walking down a soft inclined surface, there were always four marks, and this was generally the case on soft level ground, where the yielding surface was deep, so that the animal's feet sunk deeper than they could have done on a shallow soft surface, thinly spread over an unyielding one; and on places of such a nature, we frequently observed bisulcated impressions, but more frequently with marks of the posterior toes added to these. On observing the animals walking over an unyielding horizontal surface, it was quite evident that the two posterior toes generally touched the ground when the animals took long steps, and it is clear that this brings the posterior toes nearer to the ground, by causing the legs to form a more acute angle with it, than when shorter steps are taken,-the legs in the latter case forming more nearly a right angle with the ground, and resting entirely upon the two anterior toes, as is generally the case when standing upright. They thus leave on the ground a bisul cated impression, provided the surface be not too soft, or the yielding portion too deep, as mentioned above. On ascending an unyielding inclined surface, the two posterior toes never touched the ground; on descending the same, they generally did so, however. From the foregoing remarks, then, it appears, that, on comparatively hard ground, where the impressions are slight, the marks made may be either bisulcated, or have in addition those of the posterior toes, on a horizontal surface; always bisulcated on ascending an inclined surface; but on descending the same, will generally present, in addition, the marks of the posterior toes; but this may or may not happen, according to the inclination of the surface. The general conclusion to be drawn from these observations we think is, that the impressions made by the feet of the sow on the ground, vary according to the softness, depth, and position of the soil over which the animal may have passed; and though it seems to be true, that, in general, there are four impressions, viz. of the two anterior and two posterior toes, still it seems equally true that the same animal may, in certain circumstances, leave a bisulcated impression, or that of the two anterior toes only. April 1829. On the Tertiary Fresh-water Formations of Aix, in Provence, including the Coal-field of Fuveau. By RODERICK Impey MURCHISON, Esq., and CHARLES LYELL, Esq. junior, Secretaries to the Geological Society; with a Description of Fossil Insects, Shells and Plants, contained therein; by JOHN CURF. L. S.; J. De C. Sowerby, Esq. F. L. S., and J. LINDLEY, Esq., Professor of Botany in the London University. Communicated by the Authors. TIS, WE are induced to offer the following sketch of the tertiary district around Aix, in Provence, from finding that several of the testacea and plants which we collected there last summer belong to species hitherto undescribed; and more particularly that we may point out the geological position of certain fossil insects, of which Mr Curtis has added some interesting figures, and a description. A portion of this district has already been described by M. Bertrand Geslin *, and as a still more detailed account of the whole country is shortly expected from the pen Sur le Bassin Gypseux d'Aix, &c. Mem. de Hist. Nat. de Paris, tom. i. part 2. p. 273. of M. Elie de Beaumont, we shall confine ourselves to such a line of section as may illustrate the objects above alluded to. The oldest and fundamental rock of this district, is a secondary limestone, comtaining Belemnites, Gryphites and Terebratulæ, which, in highly inclined and contorted strata, rises to the lofty and peaked summits of Mont St Victoire. This rock is referable to some member of the Jura limestone, and unconformably deposited thereon is the vast fresh-water formation we are about to describe. The town of Aix is situated in the lowest part of a deep valley, running from E. to W., the immediate flanks of which are composed of this overlying deposit. On the northern side of the valley the strata rise to the height of many hundred feet above the town; and the high road from Paris descends over a denuded escarpment of strata, which may, for our present purpose, be grouped together in the following manner : Upper Beds. White calcareous marls and marlstone, passing occasionally into a calcareo-silicious grit, used as millstones, with a band of resinous flint. This system contains a small and undescribed species of Cyclas, named gibbosa by Mr Sowerby, Potamides Lamarckii, Bulimus terebra, B. pygmeus, and a new species of Cypris. Below these beds, which form the cap of the range, are marls, both argillaceous and calcareous, containing many species of fossil plants, some of which, together with seve. ral others occurring in the inferior gypseous beds, have been examined by Mr Lindley, whose account of them will be found at the end of this memoir. The amount of thickness of these overlying beds is at least 150 feet. Here the subjacent strata run out horizontally into a terrace, in which is placed the upper zone of gypsum, and which is reached by a highly inclined flight of steps sunk through beds of marlstone and marl. These gypsum quarries had long been celebrated for their prodigious number of fossil fish and plants, but the discovery of insects is of very recent date; and their occurrence was first made known to the scientific world by M. Marcel de Serres*. In our examination of the exact position of these remains we descended about 260 steps, through marls and marlstones, abounding in plants, fish, and an occasional shell; and, on reaching the gypsum gallery, we observed the following order : *Bulletin des Sciences, vol. viii. p. 181. (No. 15.) 1. The roof called "Les Caniards"- 2. “ La Noire”—dark green and white fine laminæ of marl, with F In. 2 0 0 2 3. "La Figuette"-fine foliaceous marl, with some gypsum, 0 5 4. "La Feuille"-compact bituminous marlstone, light green co lour, 5. "La Feuille à Poisson," or Bed containing many Fish-a light brown finely laminated marl, with a polished upper surface, contains also several plants, including the Flabellaria Lamanonis? Ad. Brongniart, 0 2 0 2 6. "Feuille à Mouche," or Insect Bed.-This is a brown greenish, or light grey calcareous marl, effervescing briskly with acids, fetid under the hammer, very thinly laminated, and is the only bed in which insects have been found; with these are, however, associated an occasional Potamides, and leaves of plants, O 2 By the aid of the lens, it may be seen that there are sometimes more than seventy distinct laminæ in the thickness of an inch, being about as thick again as ordinary printing paper, often preserving a very uniform thickness, and sometimes one of them is equal to from five to ten of the others. Although the rock may be divided at almost any of these laminæ, it generally requires a sharp blow of the hammer. An impression of the form, together with different parts of the insect, is seen both on the upper and under laminæ, as in the case of the Monte Bolca fishes. 7. "Feuille de Diablon"-more compact, and passing below into gypsum, 0 24 8. "Le Diablon"-first good bed of hard workable gypsum, thinly laminated, of whitish brown colour, and containing an occasional nodule of silex, 0 6 9. "La Premiere Blanche"-best quality of saccharoid gypsum, colour white and pink, with large stems and leaves of Flabellaria, 10. "La Seconde Blanche"-saccharoid gypsum, less white than the above, 08 0 5 12. "La Rouge”—reddish tinge, contains amongst others leaves resembling those of Laurus dulcis, or cinnamon? 13. "Les Queirons"-with occasional silex, vegetable stems, and minute plants, 14. “La Soutanne"-gypsum becoming of bad quality, with an occasional Potamides, 15. "La Tuf" fetid coarse gypseous marl, forms the bottom, and 16. "Pierre Froide," or Dead Bed-compact argillaceous marlstone. 0 6 |