A Description of the genus Malesherbia of the Flora Peruvi ana; with Remarks on its Affinities. By Mr David Don, Libr. L. S.; Member of the Imperial Academy Naturæ Curiosorum, of the Wernerian Nat. Hist. Society, &c.

THE characters and habit of Malesherbia appear to me sufficiently important to establish it as the type of a distinct natural group, to which the name of Malesherbiaceae may be given. The necessity of attending minutely to the structure, both of the flower and fruit, is now universally admitted; and I wish it were as generally allowed, that the object of the botanist should be rather to point out the real structure and affinities of individuals, than to attempt extensive and unnatural combinations, in the present infantine state of botanic science: for it must be admitted, that nothing is more injurious to a system, than the unnatural association, either of genera or species; and perhaps nothing has tended more to retard the advancement of systematic botany, than the fear of an unnecessary multiplication of names, thereby inducing the contracted notion of retaining entire many heterogeneous orders and genera. If we but turn our eyes over the pages of works professing to be general Systems of Plants, we will find abundant evidence of the justness of what has been advanced; and if we but consider how few individuals in any of the extensive genera or orders have been investigated with that care and precision by which the true nature of their parts, and their relative affinities, can alone be ascertained, we should not perhaps be so averse to their separation into smaller groups. The Malesherbiacea agree on the one hand with Passifloreæ, and on the other with Turneracea. They differ from the former in their erect ovula; in the insertion of the styles; in their ascending incumbent anthers; in the placentæ not extending above the separation of the valves; in their naked seeds; in their thick, fleshy, almost hemispherical cotyledons; and finally, by their great difference in habit, and by the absence of stipules at the base of the leaves. From the latter (Turneracea), with which they agree well in habit, and in the structure of their fruit, in their erect ovula, in the structure of the anthers, and in the furrowed nature of their seed-covering; they are essen

tially distinguished by the presence of a corona, and in the persistent nature of the inner series of the floral envelope; by their incumbent anthers; by the insertion of the styles; by the pla centæ being confined to the lower half of the capsule; by their straight embryo, and by the form of the cotyledons; and, lastly, by the absence of the fleshy scale (probably the rudiment of an arillus) at the base of the seed. The Malesherbiaceæ appear to be related also in a certain degree to Loaseæ, whose characters and affinities are yet but imperfectly understood. M. Auguste de St. Hilaire, in his valuable memoir on the affinities of the Cucurbitaceae, has already pointed out the affinity of Turneraceae and Loase to Passifloreæ.

The genus Malesherbia was established by Ruiz and Pavon in their Genera Plantarum Flora Peruviane et Chilensis, published in the year 1794, and dedicated to the memory of the unfortunate M. Lamoignon de Malesherbes, a distinguished philosopher, and a great lover of botany, who fell a victim to his zeal for the cause of justice and humanity, and for the honour and glory of his country, in the early part of the French Revolution. The genus was subsequently published by Cavanilles, in the fourth volume of his Icones Plantarum, under the name of Gynopleura; but what was his object in changing the name does not appear, neither is it a matter of any importance. I shall now proceed to give a botanical description of the group, which may equally be considered as that of the genus.

MALESHERBIACEÆ.

PASSIFLOREARUM genus, Juss.

Perianthium monophyllum, tubulosum, membranaceum, inflatum, coloratum, nervis decem in limbo diffusè ramosissimis, è basi sursum peragratum: faux coronâ continuatâ brevissimâ membranaceâ v. acutè dentatâ v. 10-lobâ, laciniis 2-4-dentatis, ornata: limbus duplici ordine 10-fidus, uterque persistens, patulus, æstivatione imbricatâ; interiore petaloideo, æstivatione convolutâ. Stamina 5, hypogyna, exserta, apici columnæ inserta, laciniis interioribus perianthii opposita: filamenta filiformia, glabra, compressiuscula: antheræ lineares, retusa, biloculares, filamentis mediatè annexæ, incumbenti-erecta: loculis parallelis, margine longitudinaliter dehiscentibus, ab insertione filamenti ad apicem ferè usque confluentibus.

Pistillum: ovarium apici columnæ adnatum, subglobosum, obscurè triangulare, uniloculare: ovulis erectis, biseriatim indefinitis, fu

niculo umbilicali stipitatis: styli 3, longissimi, capillares, glabri, persistentes, valvis capsulæ alternantes, et inter ipsarum bases inserti: stigmata simplicia, clavata, disco concavo pruinoso. Capsula elongata, trigona, 1-locularis, apice trivalvis, dehiscens, polysperma, basi membranacea: valvis crustaceis.

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Placenta costa 3, prominentes, funiculis persistentibus seminiferis stipatæ, parieti capsulæ infra dehiscentiæ locum insertæ, axique valvarum perpendiculares.

Semina erecta, obovata, ventricosa, duplici serie ordinata, fuscescentia, funiculo umbilicali stipitata, apice strophiolâ fungosâ laceratâ, basi umbilico tuberculiformi aucta, extùs sulcis plurimis parallelis æquidistantibus longitudinalibus transversè rugulosis notata: testa duplex; exteriore crustaceâ, crassiusculâ; interiore cartilaginea membranaceâ: albumen copiosum, carnosum, aqueopallidum. Embryo erectus, teres, axilis, lutescens, albuminis ferè longitudine: cotyledones orbiculatæ, crassa, hinc convexæ, inde planæ, penè hemisphærica: radicula teres, crassa, obtusissima, recta, cotyledonibus longior, centrifuga.

Plantæ (Peruviæ v. Chili apricis propriæ) erecta, ramosissimæ, pubescentes, caule infernè suffruticoso. Folia alterna, simplicia, exstipulata. Flores numerosissimi, axillares v. terminales, solitarii, sessiles, lutei.

MALESHERBIA, Ruiz et Pavon, Gen. Plant. Fl. Peruv. et Chil. p. 45.

Gynopleura, Cav. Icon. iv. p. 52.

Obs. Character idem ut in ordine.

SPECIES.

1. M. thyrsiflora, foliis lineari-lanceolatis acutis sinuato-dentatis tomentosis, perianthii fauce coarctatâ, coronâ decemfidâ : laciniis 2-4-dentatis.

Malesherbia thyrsiflora, Ruiz et Pavon, Fl. Peruv. et Chil. iii. p. 30. t. 254.-Syst. Veg. Fl. Peruv. et Chil. p. 79. Gynopleura tubulosa, Cav. Icon. iv. p. 52. t. 375.

HAB. In Peruviæ apricis argillosis provinciarum Cantæ, Huarocheri, et Caxatambo (Ruiz et Pavon, Dombey); prope oppidum Purruchuco, 18 leucis à Limâ frequens, etiamque juxta Obragillo et San Buenaventura.-Ludovicus Née. h.

Floret Aprili et Maio.

Planta suffruticosa, 2-3-pedalis, foetida, hirsutissima. Folia conferta, sessilia, lineari-lanceolata, acuta, obtusè sinuato-dentata, suprà leviter canaliculata, basi aliquantulum attenuata, 2-3-uncialia. Flores flavi. Perianthium tubulatum, sesquipollicare. Corona laciniis alternis exterioribus segmentis perianthii oppositis angustioribus, plerumque bidentatis.

2. M. paniculata, foliis oblongis obtusis pinnatifidis ciliatis, perianthii fauce dilatatâ, coronâ simplict acutè dentatâ.

Gynopleura linearifolia, Cav. Icon. iv. p. 52. t. 376.?

HAB. In Chili boreali.-Alexander Caldcleugh. h. (v. s. in Herb. Lamb.)

Planta erecta, pyramidato-ramosissima, leviter canescens, 3-4-pedalis. Rami teretes, pube subtili vestiti. Folia alterna, sessilia, nunc basi auriculatà amplexicaulia, oblonga v. lanceolata, obtusa, pinnatifida, pube sericeâ pilis plurimis setaceis intermixtâ potissimùm ad margines ornata, uninervia, nervo pinnatè ramoso, patentia, semipollicem v. pollicem longa, et 3 lineas v. semiunciam lata; ultima lineari-oblonga, sæpe integra: laciniis oblongis obtusissimis; infimis duabus majoribus, stipulas simulantibus. Flores paniculæ modo dispositi, numerosissimi, pallidè lutei, siccitate violacei! pedicello brevissimo crasso suffulti. Perianthium copiosè villosum, unciale: tubus angustus, cylindraceus, imâ basi callosâ : faux dilatata, campanulata, tubo duplò triplò ve longior corona simplici, tenuissimè membranaceâ, multidentatâ, dentibus brevibus acutis inæqualibus, è nervorum calycinorum ramis lateralibus arcuatis ortum ducente: limbus duplici ordine 10-partitus, uterque persistens, coloratus; laciniis exterioribus calycinis, lanceolatis, obtusis, æstivatione imbricatis ; interioribus petaloideis, alternantibus, ovato-lanceolatis, mucronulatis, lateribus parum inæqualibus, magis coloratis, æstivatione convoluto-imbricatis, basi aliquanto attenuatis. Nervi perianthi adhuc simplices, ad summitatem tubi in ramos tres divisi; alternis ramulo intermedio in laciniis petaloideis ramosissimè diffuso; calycinarum laciniarum ramulis lateralibus brevissimè distinctis, àrcuatis, cæterùm confluentibus. Cætera ut in ordine.

For numerous specimens, both in flower and fruit, of this curious species, we are indebted to our highly valued friend Alexander Caldcleugh, Esq. F. R. S. & F. L. S. whose zeal in the cause of science is known and appreciated. He discovered it in the neighbourhood of Coquimbo in Chili, together with many other new and equally interesting plants, a complete collection of which he has transmitted to Mr Lambert. It may possibly prove to be the same with the plant of Cavanilles above quoted, notwithstanding the discrepancies in the description and figure; but, as I have never seen specimens of it to compare, I dare not venture to affirm them to be identical.

Account of a Gelatinous Quartz or Siliceous Sinter, which forms the basis of varieties of Old Red Sandstone. By M. T. GUILLEMIN.

As this interesting mineral occurs in some of the sandstone of

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this country, we have drawn up the following account from a memoir of Guillemin, published in the Annales des Mines for 1826.

External Characters.-This mineral is of a pretty pure white colour, which, in some varieties, passes into greyish or yellowish white; it has a resinous or semiresinous lustre, and passes into dull; it presents itself in irregular masses; its fracture is sometimes conchoidal, sometimes subconchoidal or even; it is scarcely translucid on the edges; when dull, it is opaque; it scratches glass with difficulty, and is scratched by steel; it is easily frangible; it adheres to the tongue, and is capable of absorbing a large quantity of water; its specific gravity varies according to the quantity of liquid which it contains.

When immersed in distilled water, gaseous bubbles are speedily disengaged, which rise after one another; and, at very short intervals, a, whizzing noise is emitted, and from time to time cracks are heard; a fissure then forms, and gives rise to a new column of bubbles. At the end of twelves hours, there are still bubbles escaping; after eighteen hours the absorption appears complete. If boiling water be used, the disengagement is much more rapid, and by means of it bubbles are still made to rise from a fragment that has been immersed in cold water for several hours, and which appears saturated. A fragment of about five grammes weight, already containing 11.11 per cent. of water, according to a trial made at the moment, still absorbed 14.36, in all 25.47 per cent. at the temperature of six degrees of the centigrade thermometer. A hundred parts of this substance, therefore, saturated with water, contain 20.30. Another fragment of about 10 grammes, dried before immersion, absorb ed 24.51 per cent. of water at zero, or about a fourth of its weight, as in the preceding experiment.

These specimens, left to themselves for two or three hours,

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