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exhibit the arched bundles of vascular fibres which compose the ligneous cylinder, surrounded by the cellular tissue. From the stellated markings produced by sections of the vessels that compose the tissues, and are visible to the unassisted eye, these fossils have obtained the popular name of Staar-stein or Star-stones.

Recent investigations have shown that these stems consist of two distinct parts; namely, an inner axis, surrounded by a zone composed of numerous cylindrical bundles of vessels, which are supposed to be roots that proceeded from the stem near its base. In the exterior portion the air-roots have a vascular tissue, but there is in many examples a delicate interstitial cellular tissue. In the axis, the vessels form zigzag or vermiform bands resembling those in ferns, and which are entirely composed of barred or scalariform vessels. The Psarolites are therefore considered by M. Adolphe Brongniart to be the bases of the trunks of lycopodiaceous trees; while M. Cotta and others regard them as true arborescent ferns. The external surface of the specimens I have examined has a ligneous structure, and is of a dark reddish brown; internally they are of a dull red colour mottled with various tints of blue and yellow, from the infiltrated chalcedony with which the vessels of the tissues are more or less permeated.1

ASPHODELEE (Clathraria, Endogenites, Dracana).- Case E. On the lower shelves of this case there are specimens of three remarkable fossil plants; two of which were first discovered by the Author in the Wealden deposits of Tilgate Forest; the other by Mr. Bensted in the Kentish-rag near Maidstone. They are placed under the name Asphodeleœ.

CLATHRARIA (C. Lyellii).-Case E [5].-The Clathraria (latticed-stem), so named from the appearance of the cicatrices left by the petioles, is a remarkable tribe of terrestrial plants allied to the Cycadeæ, that flourished during the period when the Wealden beds of the south-east of England, and the lowermost and middle cretaceous strata were deposited; for remains of these plants occur in the greensand and chalk marl. All the specimens in the Case were collected by the Author

1 Beautiful coloured figures are given in “Pictorial Atlas of Organic Remains," Pl. VIII. M. Cotta has published an able work on the subject, in which nearly thirty species are described. See also M. Brongniart's "Tableau des Genres de Vég. Foss." p. 44.

from the calciferous grit of Tilgate Forest; and they form a highly instructive series, comprising portions of stems scored with the imprints of the petioles, the internal imbricated axis, leaf-stalks, and indications of the foliage and flower-buds.

LIGN. 15.-WATERWORN SPECIMEN,

SHOWING THE EXTERNAL SURFACE

OF THE STEM OF CLATHRARIA LY

ELLII.

WEALDEN.

The stem of the Clathraria is composed of an axis or internal column, the surface of which is covered with reticulated fibres. The large branched fossil lying on a slab of stone in the middle of the case, is the finest specimen of this part hitherto obtained: it was discovered, with bones of the Iguanodon, in a quarry near Cuckfield, Sussex, in 1820. The axis is invested with a very thick bark formed of the consolidated bases of the leafstalks, the insertions of which are rhomboidal and transverse. The outer surface of the bark is in consequence marked with elevated lozenge-shaped cicatrices, separated from each other by a marginal furrow, which is surrounded by a parallel ridge or band of a fibrous structure. The cortical portion of the stem is in general converted into a cylinder of stone, which in some instances will separate from the axis. There is a beautiful specimen of this kind in the case; and likewise one in which the axis projects, and is surrounded by the bark.' The axis is solid, and has its surface strongly marked with interrupted reticulated ridges. This surface has generally patches of vascular tissue adhering to it; and on some parts there are deep pits or lacunæ, which probably contained a resinous secretion. I have spared neither trouble nor expense in endeavouring to detect the organization of this plant; scores of sections of stems have been made and examined microscopically, but very few specimens exhibit any

[graphic]

(nat. size.)

1 This, and the large branched specimen of the axis, were first described and figured in my "Fossils of Tilgate Forest," Pl. I.

traces of structure; and in those which retain some vestiges of organization, the siliceous mass into which the vascular tissue is transmuted, is not sufficiently transparent to yield satisfactory results; it can only be inferred that in their internal organization, as in their external characters, the Clathrariæ were most nearly allied to the Cycadeæ or Zamiæ. A remark

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The summit of a stem garnished with petioles; the lower part shows the cicatrices left by the removal of some of the petioles: a, the internal axis.

able specimen discovered in a stratum of chalk marl near Bonchurch, in the Isle of Wight, throws much light on these interesting plants: and I insert a figure, to illustrate the fossils in the case before us. It consists of the summit

1 This specimen is in the collection of Captain Ibbetson, F.R.S.

of a stem garnished with persistent petioles or leaf-stalks; it is fifteen inches in length, is perfect at the top, and at the fractured end the internal axis, surrounded by the false bark formed by the confluence and consolidation of the bases of the petioles, is exposed. (See Lign. 16, a). The stem at the lower part is bare, and exhibits the characteristic lattice-like scars. The petioles are for the most part entire ; some of them are abortive, and others which have supported leaves are marked on the summits with vascular pits, indicating that the foliage was shed naturally.'

There is a fragment of an internal axis, about six inches in length, that is placed near the large slab, which will interest the botanical observer, and requires a passing notice. This specimen is naturally separated transversely into two portions; the lower one is convex on the upper part, and is traversed by fibres, which extend from the outer surface across to the opposite side; the corresponding face of the other portion is concave, and closely adapted to the convexity, leaving on one side an oval hollow, which denotes the origin of a floral axis or panicle, as is proved by the direction of the fibrous structure."

From the obscure traces of leaves that have been observed in some examples, it seems probable that the foliage resembled that of the Yucca. Small kernels or seed-vessels somewhat resembling those of certain palms, as for example the Areca, are often associated with the stems of Clathrariæ, and may have belonged to those plants. The remains of these vegetables are generally deposited among gravel, or sand, with water-worn bones of reptiles; and are occasionally imbedded in the fluviatile conglomerate of the Wealden.

Endogenites Erosa.-Case E.-The stems thus labelled are also from the Wealden deposits; they often occur in the layers of lignite which traverse the clay-beds in some parts of Sussex. These stems are from one to eight inches in diameter, and five or six feet in length, and of a very irregular shape; there are no indications of branches. Some are subcylindrical in the middle, and gradually taper to a point

1 See "Medals of Creation," p. 182; "Wonders of Geology," p. 395; "Geology of the Isle of Wight," p. 292.

2 Figured in "Medals of Creation,” p. 183.

at each end; others are of a depressed clavated form, like some of the Cactea or Euphorbiæ. These fossils are generally transmuted into a hard and fine siliceous grit, and, when in situ, are invested with a friable carbonaceous bark of a glossy lustre, which soon falls to pieces on exposure to the atmosphere; so that cabinet specimens seldom retain any vestiges of this integument. When this crust of coaly matter is removed, the surface of the silicified stem is seen to be traversed by numerous fine meandering grooves, and deep, tortuous, tubular channels, disposed in an irregular manner in a longitudinal direction. These channels or vessels, which are generally lined with quartz crystals, give the surface that eroded appearance whence the specific name erosɑ was derived they are not, however, the effect of erosion, but of the original structure of the plant; they traverse the substance of the stems, and although no symmetrical arrangement is apparent, this anomaly is probably attributable to the changes which the vegetable organization has undergone during its mineralization. In one instance (a specimen from the Wealden of the Isle of Wight), bundles of vascular tissue, arranged in a flexuous zone round the margin of the cylinder, are observable in polished sections under the microscope; the structure approaches more nearly that of the Cycadea than of the Euphorbiacea, with which some botanists have associated these enigmatical plants of the Wealden flora.'

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DRACENA (D. Benstedi).-Case E.-In the lowest department of the same case are fragments of a large fossil stem allied to the Dracena, or Dragon-blood Tree, discovered by Mr. W. H. Bensted, of Maidstone, in a quarry of Kentish Rag, near that town; a locality to which we shall more particularly allude in the sequel. The largest portion is two and a half feet in length, and eight inches in diameter; the surface is marked with interrupted annular ridges, indicating amplexicaul leaves. These fossils were found associated with drifted coniferous wood, and bones of turtles and iguanodons.

Medullosa.-Case D.-In the lower division, beneath the Lepidostrobi, there are many specimens, some cut and po

1

Figured in "Fossils of Tilgate Forest," Pl. III.; "Geology of the S.E. of England," Pl. I.: by Dr. Fitton, in "Geol. Transactions," vol. iv.

E

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