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blance to alcyonium digitatum of Linnæus; or the dead man's
hand, or dead man's toes of Ellis. Its texture evidently ap-
pears to be of that kind, being finely reticulated, which
would correspond with the carneous spongy substance, of
which the recent zoophyte is formed. Its surface also,
thickly beset with minute openings, bearing somewhat of a
stellated appearance to the naked eye, serves to confirm the
resemblance, This fossil is now a carbonate of lime mode- Chalk.
rately hard, but friable.

In the elegant work of Mr. Knorr, Mr. Walsh describes Priapolithi several fossil elongated alcyonia, by the silly term which the ancients had adopted, of priapolithi. One of these from Touraine is figured, Plate VII, fig. 1. It had at its superior termination that opening, observable in many of these animals, which served for the reception of the seawater, from which, it is probable, they derived their support.

On rubbing down this substance on a sandstone, at this A retiform textermination, for the purpose of examining its structure, its ture of silex, hardness and the partial polish it obtained, proved, that it had suffered an impregnation with silica: and an examination of this surface with a lens plainly showed, that the Ainty part was regularly distributed in continuous meandering lines, bearing the peculiar and characteristic form of the spongy part of alcyonia, whilst the intervening spaces appeared to be filled by a softer substance, a carbonate of lime. The substance was therefore partly immersed in di- and the interlute muriatic acid, by which the calcareous part was speedily with chalk. removed, with effervescence, and the siliceous part left, pos-. sessing the fine retiform texture of the spongy alcyonium, surrounding the central opening already mentioned, as may be seen in the upper part of the figure.

The fossil represented Plate VII, fig. 9, approaches the nearest, in its general form and appearance, to the alcyonium cydonium Linnæi, the alcyonium primum of Discorides, or rather to the representation of this animal as given by Donati. It must however be, I believe, considered, as differing from any known animal of this genus.

This fossil is of a roundish form, rendered unequal by shallow depressions about the width of a finger, which pass

from

stices filled

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from the superior to the inferior part of the fossil, and are separated from each other by tuberculated ridges. At the upper part has been a circular opening more than half an inch in diameter; and, at the lower part, is a rugged spot as though the pedicle had been here separated: a circumstance indeed which renders its affinity to the alcyonium described by Donati rather more doubtful. The substance of this fossil appears to be a limestone, which, probably from some tinge of iron, has obtained a reddish brown colour. It is not of a very close texture, apparently from the superadded calcareous matter not having accurately filled all the interstices between the fibres. Hence numerous small openings are, even in its present state, observable on its surface, which on close inspection are seen to be such as would result from a loose or spongy texture.

Whilst treating of the alcyonium, of the species to which this seems to approach, Donati particularly describes and delineates the curiously formed spicule, which constitute a part of its substance. The body, as well as the cortical part, he remarks, is formed of two substances: the one of which is fleshy, and the other osseous. The latter, he adds, is formed into spines; which, near the cortical part, are in great number, and closely intermingled; being about the length of two lines, and even longer. They are either of a fusiform figure, or are finely pointed at one end, and then gradually enlarge towards the middle: then, diminishing as they lengthen, they divide into three sharp conical points, around which are fixed numerous minute globular bodies, which are chiefly found in the cortical part.

A very strict examination, with a lens, of the surface of numerous fossil alcyonia, did not however discover any appearance of similar spines, and almost induced me to a ready concurrence with Plancus, who relates, that he has dissected various bodies of this kind, and has seen the osseous fibres disposed in a radiated form; but as to the wonderful bark, the structure of which is so floridly described by Donati, he says, I have not seen it, and observes that the same thing has happened to him, with respect to the greater part of the figures in Donati's book, which, he says, are embellishments of the designer, drawn by the rule and

compass,

compass, rather than in agreement with the truth and simplicity of nature.

examined

Being in possession of another specimen of this kind, A specimen formed of a much harder and closer stone, and which from its appearance I supposed to be invested with its cortical part, I resolved to sacrifice it to a more rigorous search for the spines described by Donati, concluding that, since all agreed as to their differing in their bony hardness from the other parts of this animal, I should at least discover some traces of them, although I might not be able to make out their form.

This fossil was therefore subjected to the only modes of by cutting, dissection which I could employ with substances possessing a stony hardness. A polished section of it was obtained on different parts of it, and at different depths; by which the peculiar spongeous structure, already noticed as belonging to these bodies, was perceived; but no appearance of spines could be detected.

in muriatic acid,

The specimen was then immersed in dilute muriatic acid, and digestion and examined at different periods, to ascertain whether the new surfaces thus obtained displayed any particular appearance. After rather more than a quarter of an inch of its substance was thus removed, I was pleased to find, with a lens of moderate power, several cruciform spines, formed, which exhibits as it were, by two fusiform bodies, not an eighth of an inch ed the spines. in length, crossing each other at right angles, and terminating at each end in a very sharp point.

When these bodies were first discovered, the specimen These an hywas still wet with the water, with which the acid had been drophanous chalcedony removed. In this state they possessed a considerable degree of transparency, which they rapidly lost, as the water evaporated: so that when dry, they were completely opaque, and of a chalky whiteness: From their possessing this hydropbanous quality, and from their having withstood the action of the muriatic acid, there appears to be the greatest reason for supposing, that these bodies, which were originally the spines of the animal, are now formed of an by- imbedded in

• De Conchis minus notis, App. II, page 115.

YOL. XXIII-MAY, 1809.

E

drophanous

chalk.

Alcyonium resembling the

sea-fig

drophanous chalcedony, and imbedded in a matrix of carbonate of lime, which has pervaded or has supplied the place of the soft spongeous part. This and the preceding fossil alcyonia are from Switzerland.

Alcyonium ficus Linn. accurately depicted in the Metallotheca of Mercatus as Alcyonium quintum antiquorum, and particularly described by Marsilli as Figue de substance d'eponge, & d'alcion †, resembles much, in form, the brown silicious fossil, Plate IX, fig. 4. The recent alcyonium, according to the Count, is of the form of a fig, being attached to the rocks by branches proceeding from its smaller end; its upper part being a little flattened, with a hole in the middle. Its colour, he says, resembles that of tobacco, and its parenchymatous substance, he thinks, cannot be compared to any thing better than to nutgalls, when well dried. In all these respects, a very exact agreement seems to exist between the recent and fossil substances. Still, howbut different. ever, the fibres running over its surface, and penetrating its substance, with the grooves which appear to have been formed by other fibres, which are now removed, distinguish it, not only from this, but, I believe, from all known alcyWholly silex. onia. This fossil is from Wiltshire, and appears to be formed entirely of flint.

The fossil, Plate IX, fig. 3, from Mount Randenberg, near Schafhousen, in Switzerland, possesses evident marks Reticular tex- of its alcyonic origin. This fossil, like those of the ramose

ture of flint

filled with

chalk.

Another similar.

kind, figured in Plate VII, has that reticular texture, which appears to be peculiar to the spongy alcyonia. In this specimen also, as well as in those, the reticular fibres are impregnated with silica, and have their interstices filled with calcareous matter. In this, as in the fossil last described, the remains of the' pedicle, the organ, by which its attachment to its appropriate spot was accomplished, are observable; as well as the superior opening, which passes into the substance of the fossil.

The fossil represented Plate IX, fig. 5, and which is from the neighbourhood of Saumur, being a very perfect fossil

* Arm. 6. C. 6.

P. 102.

+ Histoire Physique de la Mer, p. 87.

of

of the kind described by Mons. Guettard, agrees, in its general characters, as well as in its texture, with that one which has been juft described. In this specimen, at its superior surface, there are, as Mons. Guettard observes is sometimes the case, four openings; and the pedicles, as well as its lateral processes, which appear like roots, seems to have been formed with a great degree of luxuriance.

one of the

A very perfect fossil of this kind, and similar in its sub- A very perfect stance and texture to the alcyonia, which have been just same texture. described, but of a dark red colour, where it is not invested with its cortical part, which is of a grey colour, pervaded by a slight tinge of red, is represented, Plate IX. fig. 8. The pedicle, and the opening at the superior part, care here very perfect. Slight traces of lines, passing from Fibres for the pedicle to the opening, are discoverable on this speci- drawing in and men, and, doubtlessly point out the arrangement of fibres, by which the animal was enabled to draw in and eject the -water which supplied it with food. This fossil, I have rea-son to believe, is English.

ejecting water.

VIII.

An Account of Improvements in the Culture of Vegetables, by JOHN CHRISTIAN CURWEN, Efq., M. P. of Workington Hall, Cumberland*.

SIR,

LAM fearful

you should suppose, that I am become indolent, and that the favours so liberally bestowed on me by the Society had ceased to operate as a ftimulus to the farther exertions of my humble endeavours to assist those objects, which by the fostering hand of the Society, have been so essentially promoted. You will excuse me for wishing Objects of imto assure you that I am not idle, and to inform you that the portance in agriculture.

Trans. of the Society of Arts, vol, XXVI, p. 79. The gold medal of the Society was voted to Mr. Curwen for these communications.

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