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Read also the conclusion of Dr. J. D. Hooker's "Enumeration of the Plants of the Galapagos Islands, with descriptions of the new species."

In a brief introduction Dr. Hooker offers his acknowledgements to Mr. Darwin, by whom the collection on which this enumeration is chiefly founded was made, and to Prof. Henslow, in whose charge the collection had been placed, and who kindly relinquished his intention of publishing the novelties contained in it in favour of the author. He also notices the striking peculiarities which mark the flora of the Galapagos group, the plants composing which not only differ in a great degree from those of any other country, but are in many

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cases peculiar to the separate islands, although in those instances frequently representatives of others which are found on different islands.

The number of species enumerated is two hundred and twenty-eight. Of these upwards of a hundred are described as new, and six new genera are established, the characters of which are given as follows:—

Ord. BORAGINEÆ.

Gen. GALAPAGOA, Hook. fil.

Calyx 4–5-partitus; laciniis linearibus. Corolla infundibuliformis; tubo lato; limbo 5-fido patente; fauce nudâ. Stamina 5, inclusa, imo corollæ tubo inserta. Ovarium 4-loculare. Stylus terminalis, ad basin usque bipartitus; stigmata 2, obtusa. Semina pendula; albumine parco, carnoso; cotyledonibus planis; radiculâ majusculâ, superâ.—Herbæ Insularum Galapagos, hispido-pilosœ. Caules prostrati, ramosissimi. Folia alterna, coriacea, versus apices ramulorum densissimè conferta. Flores parvi, in axillis foliorum omninò sessiles, valdè inconspicui.

Obs. Genus Ehretiearum inter Coldeniam et Rhabdiam (secund. clariss. Bentham) medium, ob stylum bipartitum staminaque fundo corollæ inserta singulare.

Ord. SOLANEÆ.

Gen. DICTYOCALYX, Hook. fil.

Calyx cylindraceus, 5-fidus; lobis acutis; tubo post anthesin subinflato, membranaceo, reticulatim venoso. Corolla membranacea, subinfundibuliformis; tubo gracili gradatim supernè ampliato; limbo plicato, brevi, vix explanato. Staminum filamenta elongata; antheræ inclusæ. Ovarium disco carnoso insertum; stigmate capitato. Capsula evalvis, indehiscens, bisulcata, incompletè 4-locularis, calyce ventricoso inclusa. Semina plurima, majuscula, tuberculata, dissepimenti medio prope angulum parietalem affixa; testâ nitidâ, obscurè granulatâ. Emoryo arcuatus.—Herbæ Americanæ, repentes, glanduloso?-pubescentes, cumtribu Daturearum, suadente Clariss. Miers, conferendœ. Folia membranacea, angulata v. sinuata, subopposita v. bina. Flores axillares.

Ord. COMPOSITÆ.

Gen. DESMOCEPHALUM, Hook. fil.

Capitula in axillis foliorum densissimè congesta, monoica, 6-flora; floribus 3 fœmineis ligulatis, cæteris masculis tubulosis. Involucrum compressum; foliolis 3–5 inæqualibus. Receptaculum minimum, epaleaceum. Corolla fœminea tubo brevi, lato, piloso; ligulâ latâ, involutâ, bifidâ: mascula 4-fida, dentibus extùs hispido-barbatis. Antherœ ecaudatæ. Stylus floris masculi indivisus, acutus; floris fœminei in ramos 2 elongatos desinens. Achenium latè obcuneatum, compressum, subtrigonum, supernè pilosum, foliis involucralibus immutatis tectum.—Genus Elviræ affine. Radix annua. Caulis pedalis, herbaceus, teres, erectus, a basi

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trichotomè divisus; ramis ascendentibus pubescentibus. Folia opposita, petiolata, ovata, obtusa, duplicato-serrata, coriacea, suprà scabriuscula, nitida, subtùs pubescentia, nigricantia. Capitula axillaria, densissimè congesta, massam depresso-sphœricam semunciam latam efformantia. Involucri foliola latè ovata, acuminata, hispida. Corolla valdè inconspicua.

Gen. MICROCŒCIA, Hook. fil.

Capilula axillaria, pauea, valdè compressa, monoica, subtriflora; floribus fœmineis ligulatis, masculis tubulosis. Involucrum compressum, 3–4-foliolatum; foliolo unico latè obovato, unilaterali, cæteris parvis collateralibus. Receptaculum minimum, epaleaceum. Corolla floris fœminei tubo gracili; laminâ rotundatâ, obscurè crenatâ: floris masculi 4-fida; tubo supernè ampliato; segmentis extùs barbatis. Antherœ semi-exsertæ, ecaudatæ. Stylus floris fœminei in ramos 2 elongatos desinens; floris masculi indivisus. Achenium cuneatum, compressum, obscurè trigonum, parcè pilosum.—Herba pusilla, repens, scaberula; ramis gracilibus, ascendentibus. Folia opposita, petioluta, rigidula, ovata, acuta, serrata, suprà hispidula, subtùs cuna, venis prominulis. Capitula minima, breviter pedicellata. Involueri foliolum exterius planum, acuminatum, nervosum, marginibus basi involutis. Flores exserti, flavi.

Gen. MACRÆA, Hook. fil.

Capitulum multiflorum, heterogamum, radiatum; floribus radii squamis involucri tectis, paucis, 1-seriatis, fœmineis; disci tubulosis. Involucri hemisphærici squamis sub-2-seriatis, disco brevioribus. Receptaculum couvexum, paleaceum; paleis deciduis flores involucrantibus. Corolla radii tubo brevi gracili, ligulâ latâ bifidâ; disci tubo 4-fido, dentium marginibus incrassatis. Antherœ breviter appendiculatæ. Stylus floris radii in ramos duos obtusos desinens; disci ramis cono latiusculo terminatis. Achœnium obovato-cuneatum, compressum, trigonum, hispidum, pappo brevi e squamis paucis ciliatis coronatum.—Genus Heliopsideis relatum. Frutex; ramis erectis virgatis, nodosis. Folia in ramis abbreviatis fasciculata, rigida, linearia, integerrima, pilosu, suprà nitida, marginibus revolutis. Pedunculi folia superantes, graciles, sericei. Capitula sphœrica. Flores flavi, radii pauci. Receptaculi paleæ lineares, apicibus incurvis acuminatis, dorso hispidis.

Ord. Incert.

Gen. PLEUROPETALUM, Hook. fil.

Calyx persistens, bipartitus; sepalis latè ovatis. Petala 5, subæqualia, libera, concave, coriacea, siccitate multicostata. Stamina 8, toro inserta; filamentis in tubum membranaceum coalitis; antheris elongatis, ovarium vix superantibus. Styli 4, lineares. Ovarium 1-loculare, pluriovulatum; ovulis placentæ basilari funiculis elongatis adnexis.—Suffrutex? perennis, glaberrima, siccitate nigricans; ramis teretibus, strictis, apicem versus foliosis. Folia petiolata, patentia, elliptica, utrinque attenuata, longè acuminata, integerrima. Flores in paniculas breves,

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Paucifloras, terminales dispositi, breviter pedicellati, inconspicui. Calyx parcus, carnosus. Petala majuscula.
Obs. Genus nulli ordini arctè affine, habitu Phytolaccœ.

January 20, 1846.

R. Brown, Esq., V.P., in the Chair.

Robert James Nicholl Streeton, Esq., M.D., and Robert Marnock, Esq., were elected Fellows.

Read a memoir "On the Structure of the Ascidia and Stomata of Dischidia Rafflesiana, Wall." By the late William Griffith, Esq., F.L.S. &c. Communicated by R. H. Solly, Esq., F.R.S., F.L.S. &c.

This paper bears date at Mergui, November 7th, 1834. In it the author gives a detailed description of the arrangement, form and structure of the ascidia of the species of Dischidia above-named, and comes to the conclusion that they are modified laminœ of leaves, in proof of which he adduces: 1st, their similarity in texture, internal structure, and structure of stomata with the limbs of the ordinary leaves; 2ndly, the slight but constant tendency in the limb of the leaves to assume an involute form; 3rdly, the occurrence of an imperfectly transformed pitcher, in which the body of the pitcher is clearly referable to the limb of the leaf; and 4thly, the general construction of the petioles in Asclepiadeœ, which renders it more natural to refer the ascidia to the limb of the leaf in that family. He regards the inner surface of the pitcher as corresponding with the upper surface of the leaves; and is confirmed in this view by the greater abundance and development of the stomata on those surfaces. On the lower and outer surfaces the stomata are more or less imperfect; but on the upper and inner they show a considerable degree of complexity. They are particularly remarkable for the existence of an external cellular bourrelet or thickening, much elevated above the surface and of a whitish colour, giving rise to an appearance of minute white dots, which are especially conspicuous on the purple inner surface of the ascidia. They appear to have a very slight connexion with the cuticle, from which they are easily detached, and are not met with on old ascidia. Each bourrelet is composed of from