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It was followed by a quivering of the earth; and after this a wind issued out of the hole, which agitated the plants round about. He watched to see whether the motion extended to any distance; but was sensible it did not reach above 3 or 4 paces from the hole, and that no motion was perceived farther off.

He further observed, that this phenomenon never happens till after the 7th wave rolls in; for it is a common thing in this country to find the sea appear calm for some time, and then produce 7 waves, which break on the coast one after another: the first is not very considerable: the 2d is somewhat stronger; and thus they go on increasing to the 7th, after which the sea grows calm again, and retires. This phenomenon of the 7 waves is observed by navigators with great attention, especially at low water, to be the better able to go in or come out the very time that the sea grows quiet. These 7 waves successively fill the caverns, which are all along the coast; and when the 7th comes to open itself, the air at the bottom of the caverns being greatly compressed, acted by its elasticity, and immediately made those fountains and gushings abovementioned; and the water continuing in the caverns, up to the very place of the hole, began to produce that dull noise, caused the emotion or earthquake, and finished with the violent wind forced up through the hole; after which the water retired into the sea, and having no further impelling cause, on account of the waves, rendered every thing quiet again.

XC. A Catalogue of the Fifty Plants from Chelsea Garden, presented to the Royal Society, by the Company of Apothecaries for the Year 1757, Pursuant to the Direction of Sir Hans Sloane, Bart. By John Wilmer, M. D. P. 648. [This is the 36th annual presentation of this kind, completing to the number of 1800 different plants.]

XCI. An Historical Memoir on a Genus of Plants called Lichen, by Micheli, Haller, and Linneus; and comprehended by Dillenius under the terms Usnea, Coralloides, and Lichenoides, tending principally to Illustrate their several Uses. Communicated by Wm. Watson, M.D., F. R. S. p. 652.

The whole class of mosses was but very little noticed by the revivers of botany in the 16th century: they indeed took some pains to distinguish the particular species mentioned by the ancients, but disregarded almost all the rest. Modern botanists however suppose, that they were but little successful in general in their application of the ancient names to plants: nor is a failure in such attempts to be wondered at, considering the too great conciseness, and frequent obscurity of their descriptions. In the class of mosses, as in many others, the accounts transmitted to us are little more than a scene of uncertainty and confusion. It

is to the moderns we are indebted for the discovery of the far greater number of the plants of this class. In this branch of botany our own countrymen Mr. Ray, Buddle, Dale, Doody, Petiver, and Dr. Morison, Sherard, Richardson, and others, have distinguished themselves: and among foreigners M. Vaillant, Sig. Micheli, and Dr. Haller: but, beyond all Dr. Dillenius has made the most ample discoveries and improvements, of which his elaborate history will ever remain a standing proof.

The word lichen occurs in the writings of Dioscorides and Pliny; and though it may be doubtful, there is yet good reason to apprehend, that Dioscorides meant to describe under that name the very plant, or at least one of the same genus, to which the commentators agreed to affix his description. Since then the name has been variously applied by different authors; on which account it is necessary to premise, that the lichen sive hepatica off, or liverwort of the shops, does not fall under this generical term, as it is now formed by the 3 abovenamed authors. They comprehend under the term lichen, and Dillenius under those of usnea, coralloides, and lichenoides, the hairy tree moss or usnea of the shops; the muscus pulmonarius, tree lungwort, or oak lungs; the lichen terrestris cinereus, or ash-coloured ground liverwort; the coralline mosses; the cup mosses; horned mosses; the orchel, or Canary-weed; the muscus islandicus of Bartholine; and a multitude of others found on trees, walls, rocks, and stones, in all parts of the world, and in many parts thereof in very great abundance.

Caspar Bauhine, in his Pinax, John Bauhine, and our countrymen Gerard and Parkinson, and their contemporaries, as they wrote before the time that generical characters in botany were in use, included these lichens among the other herbaceous mosses, under the general name of muscus; adding to the name in general some epithet descriptive of its form, place of growth, or supposed virtue. Mr. Ray, both in his History of Plants, and in the supplement, as he was usually averse to the forming of new names, has interspersed them among other mosses, under the character of musci steriles seu aspermi, retaining the synonyms of the two Bauhines, Gerard, and Parkinson, to the general species.

Dr. Morison seems to have been the first, who separated them entirely from the herbaceous mosses; and, from the analogy he supposed they had with the fungus tribe, formed them into a genus, under the name of musco-fungus. He enumerates 50 species and upwards under this term in the Historia Oxoniensis, and has divided them into 5 orders, according to their different appearances, as follows:

1. Musco-fungi e terra prominentes, latiores. 5.-2. Musco-fungi pixidati. 11. -3. Musco-fungi corniculati. 26.-4. Musco-fungi crustæ modo adnascentes. 37.-5. Musco-fungi corticibus arborum dependentes. 53.-Table the 7th of his 15th section exhibits several good figures of some of these lichens.

Tournefort was the first who adapted the generical term lichen to them; but it was in consequence of his joining them to the lichen of the shops. He has however excluded the coralline-mosses, and forms them into a genus, by the name of coralloides; to which he has connected some plants, properly of the fungus tribe. In this distinction he is followed by Dr. Boerhaave in his Index alter Plantarum.

Dr. Dillenius first called them lichenoides in the catalogue of plants growing about Giessen, choosing to retain the word lichen to the liverwort of the shops. Under this name however, in this work, he does not comprehend the usneæ, or hairy-tree mosses, but refers them to the confervæ, adding the epithet arborea to each species, to distinguish them from the water kinds. He enumerates upwards of 60 species of lichenoides, but has applied few or no synonyms to them. Under the same generic term he has introduced them into the 3d edition of Ray's Synopsis of British Plants, taking in the usneæ, and recounting upwards of 90 species, all found spontaneously growing in England. Many of these are doubtless only varieties. They are in this work very naturally divided into several orders and subdivisions, for the greater ease of distinguishing them, as follows: 1. Capillacea et non tubulosa scutellata.


2. Coralliformia tuberculosa plerumque. {a. Solida et non tubulosa.

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cauliculis destituta.

1. Mere crustacea.

b. Tubulosa.

2. Crusta foliosa scutellata seu foliis a. Substantiæ gelatinosa.
scutellatis arcte adnascentibus. {. Substantiae duonos

3. Foliis magis liberis nec tam a. Scutellatis et tuberculatis,
arcte adnascentibus.
{b. Pelati

M. Vaillant, in the Botanicon Parisiense, retains Tournefort's names. Many of these lichens, as well as other mosses, are accurately represented in the elegant tables which adorn that work. Dr. Haller tells us he learnt to distinguish almost all the mosses solely by the help of these tables, so well are they expressed. The lovers of botanic science are greatly indebted to Boerhaave for his publication of that work.

Micheli, after Tournefort, adopts the term lichen, and comprehends all the species under it, except one or two, which he calls lichenoides. This author, however does not take into this genus the liverwort of the materia medica; he describes the species of that genus under the name of marchantiæ. Near 20 of the plates in his Nova Plantarum Genera are taken up in representing various species of this genus. In this work they are divided into 38 orders or subdivi sions; a circumstance very necessary indeed, considering how greatly he has multiplied the number of the species. It is to be regretted, that so indefatigable an author, one whose genius particularly led him to scrutinize the minuter subjects


of the science, should have been so solicitous to increase the number of species under all his genera: an error this, which tends to great confusion and embarassment, and must retard the progress and real improvement of the botanic science. Dr. Haller retains Micheli's term, and enumerates 160 kinds in his Enumeratio Stirpium Helvetiæ; he divides them into 7 orders, according to the following titles: 1. Lichenes corniculati et pixidati.—2. Lichenes coralloidei.—3. Lichenes fruticosi alii.-4. Lichenes pulmonarii.-5. Lichenes crustacei scutis floralibus ornati.-6. Lichenes scutellis ornati.-7. Lichenes crustacei non scutati. The extensive number of the species, and the difficulty of distinguishing them with a tolerable degree of certainty, has deterred Dr. Haller from adding so full and complete a list of synonyms to the plants of this genus as he has elsewhere done in that splendid work. Plate the 2d exhibits several elegant sorts of these lichens.

Linneus, and the followers of his method, who seem to have established their generical character from Micheli's discoveries, retain also his generical title. Micheli's passion for the multiplication of species is no where more conspicuous than in the plants of this genus, which he has most enormously augmented to the number of 298 species. The Swedish professor cannot be charged with this foible: it is one of the excellencies of his writings, that they inculcate the reverse. He has so far retrenched this genus, that in his general enumeration of plants he recounts only 80 species belonging to it. They are in this work divided into 8 orders, according to the difference of appearance which they form by their facies externa, little or no regard being had to what are usually called the parts of fructification. 1. Lichenes leprosi tuberculati.-2. Lichenes leprosi scutellati. -3. Lichenes imbricati.-4. Lichenes foliacei.-5. Lichenes coriacei.-6. Lichenes scyphiferi.-7. Lichenes fructiculosi.-8. Lichenes filamentosi.

Dr. Dillenius, in his work, intitled, Historia Muscorum, has divided this Michelian genus into 3, under the names of usnea, coralloides, and lichenoides. Under the word usnea he comprehends the hairy-tree mosses, among which are the usnea of the shops, and the true usnea of the Arabians. Of these he describes 16 species. Under coralloides he describes 39 species, among which are the cup mosses, and many others, disposed according to the following scheme: Ordo 1. Fungiformia, non tubulosa, nec ramosa, 5. Ordo 2. Scyphiformia, tubulosa, simplicia et prolifera.

Series 1. Scyphis perfectioribus. 13. Cup mosses.

Series 2. Scyphis imperfectis. 20. Horned mosses.

Ordo 3. Ramosa fruticuli specie summitatibus acutis multifariam divisis.

Series 1. Species tubulosa. 30. Tubulous coralline mosses.

Series 2. Species solidæ. 39. Solid coralline mosses: among which is the

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The genus of lichenoides contains 135 species, disposed according to the following scheme:

Ordo 1. Species aphyllæ mere crustaceæ. {

Ordo 2. Species foliosa.

1. Tuberculosæ. 8.
2. Scutellatæ. 18.

1. Gelatinosæ tuberculosæ et scutellatæ. 35.
2. Aridiores et exsuccæ, scutellatæ. 100.
3. Aridiores peltatæ et clypeatæ. 121.

These plants are not only largely described, and accompanied with the most perfect assemblage of synonyms, but every species is accurately figured, and many of them in various views, and at different ages of their growth; by which this laborious work, notwithstanding it is conversant on the minutest, and consequently the most abstruse parts of botany, may yet be justly esteemed, without any exaggeration, one of the most complete works extant of the kind. Dr. Hill, in his History of Plants, has disposed them into 5 genera, under the following names: 1. Usnea, comprehending the hairy tree-mosses; 2. Platysma, flat-branched tree-mosses, the lungwort, and others; 3. Cladonia, containing the orchel and coralline-mosses; 4. Pyxidium, the cup-mosses; 5. Placodium, the crustaceous mosses. The plants of this extensive genus are very different in their form, manner of growing, and general appearance: on which account those authors who preserve them under the same name, saw the propriety and necessity of arranging them into different orders and subdivisions, that the species might be distinguished with greater facility. On the same principle Dr. Dillenius and Dr. Hill have formed them into several genera.

So far as the parts of fructification are distinguished in these plants, they appear in different forms on different species; on some, in the form of tubercles; on others, in the form of little concave dishes, called scutellæ; on others, of oblong flat shields or pelts. All these are conceived by Micheli and Linneus to be receptacles of male flowers. The female flowers and seeds are suspected by the same authors to be dispersed in the form of farina or dust on the same plants, and in some instances on separate ones. Dillenius has not dared to determine any thing positive with regard to the real parts of fructification in these lichens: time will hereafter, it is to be hoped, throw more light on the subject.

In order to convey a more distinct idea of the several plants of this genus, which enter into economical or medical uses in the various parts of the world, we shall distribute them into several orders, according to the custom of former writers and as it is not consistent with our plan to describe each of these species, we shall refer to the page of the more modern authors, where they may be found. 1. LICHENES FILAMENTOSI.

Such as consist of mere solid filaments, of a firm and solid but flexible tex

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