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retains the bark-scales modified by pressure of the Strobilus or cone that grew from the centre of the disk. The upper portion of the Scar is without indications of bark-scales, and is covered with radiating furrows, inpressed on it by the long slender scales of the base of the Strobilus, which have obliterated the bark-scales.*

The character of this scar approaches to that of Fig. 5, but its proportions differ, measuring 34 inches in the longer, and 2 inches in the shorter diameter. The scaly bark (which in Fig 5 has been almost entirely removed from the area of the scar,) is preserved on the lower portion of the disk of Fig. 6. Scale two-ninths. (Original.)

Fig. 6'. Cast of Ulodendron Conybearii (nobis) formed by Pennant sandstone of the Coal formation at Stapleton near Bristol. This cast expresses the exact form of an oval scar, or cavity on a stem from which a cone had fallen off.

The disk is covered with slight ridges and furrows, radiating in all directions from the point of insertion of the cone, and formed by pressure of its lowest scales upon the portion of the stem to which it was attached. Beneath the point of insertion, a few small

*The portions above and below the line drawn across Fig. 6, are copied from two scars in Rhode's figure. Rhode considers these impressions to be flowers, and the compressed bark-scales to be the Petioles of the flower, and has represented the trunk in an inverted position.

As, in every species of Ulodendron which we have seen, the furrows produced by scales at the base of the cone, are deepest on the upper portion of the Scar, we infer from this circumstance that the cones were inclined upwards and inwards, with their axis approximating to that of the stem from which they issued.

scales of the bark remain adhering to the Sandstone. Scale one-fourth. (Original.)

Fig. 7. Portion of the Trunk of Favularia, one-fourth nat. size. This plant is distinguished by the tessellated appearance of the scales, which cover the space between each fluting of the Bark. In the centre of the area of each scale is a club-shaped scar, which gave origin to a leaf; it was a dicotyledonous plant, probably allied to Sigillaria; and its stem must have been covered with a mass of densely imbricated foliage. In the Genus Sigillaria the leaves were more distant from one another. The Rows of scars are separated by a groove, Fig. 7. b.; their disposition in the vertical direction is indicated by the line a. (Lindley, Foss. Fl. Pl. 73.)

Fig. 8. Reduced from Lindley and Hutton's figure (Pl. 31) of the central portion of a Stigmaria ficoides, from Shale in the roof of the Jarrow colliery near Newcastle. We have here a view of the inferior surface of this curious plant. Its dome-shaped hollow central trunk, or stem, was three feet in diameter, and fitted to sustain horizontally in a floating position the numerous long branches by which it was surrounded; these divide into two, at a certain distance from the Trunk. When perfect, and floating in water, its appearance must have resembled the form of an Asterias. On the two longest branches, a. b. is seen the longitudinal depression, which is usually adjacent to the small internal woody axis of these branches, and from its position in this fossil, we learn that the place of this depression was on the inferior surface of each branch. Scale one-twenty-fourth. (See V. I. p. 358.)

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Fig. 9. Vertical section of the dome-shaped trunk of Stigmaria, showing the relative position of the branches. (Lindley and Hutton.)

Fig. 10. Restored portion of a branch of Stigmaria showing the manner in which the long cylindrical leaves proceeded from the tubercles around its surface to the length of many feet. In front, extending from a. to b. is seen the depression adjacent to the internal eccentric woody axis a. From b. to c. this axis is laid bare by the removal of a portion of the sandstone. This part of the axis is drawn from a specimen in the Oxford Museum. Scale one-seventh. (Original.)

Fig. 11. Fragment of a branch of Stigmaria, showing the character of the Tubercles, which formed articulations with the bases of the leaves. The enlargement of the leaf towards its base (a) seems to have been calculated to strengthen this part, and to afford space for the articulating socket. This socket formed, with the spherical tubercle, a universal ball and socket joint, admitting of motion in every direction. to a long cylindrical leaf floating in water. Scale one-half. (Sternberg.)

PLATE 56. V. I. p. 363 et seq.

Appearances presented by longitudinal and transverse sections of recent and fossil Coniferous woods, cut into thin slices, and magnified 400 times. (Nicol.)

Fig. 1. Longitudinal Section of Pinus Strobus, cut parallel to a medullary ray.

Fig. 2. Transverse Section of the same.

a. a. Portions of concentric annual layers.

Fig. 3. Longitudinal Section of Araucaria Cunninghami. Fig. 4. Transverse Section of the same.

Fig. 5. Longitudinal Sections of Araucaria excelsa, showing polygonal disks, in double and triple rows, on the surface of the longitudinal tubes. Some of the tubes are without disks, as in all Coniferæ.

Fig. 6. Transverse Section of Araucaria excelsa. a. Portion of concentric annual layer.

Fig. 7. Radiating and concentric structure of a branch of Pinus, as seen by the naked eye in a transverse section; the microscopic reticulations are omitted (See V. I. p. 365. Note.)

a. a. Concentric annual layers, indicating periodical growth.

Fig. 8. Longitudinal Section of Pinus, showing the relative positions of the longitudinal vessels and medullary rays.

a, Longitudinal vessels, forming the woody fibres. b, Medullary rays.

PLATE 57. V. I. p. 371.

Sections exhibiting the silicified remains of Coniferæ and Cycadeæ, in their native bed, between the Portland and Purbeck stone, on the coast of Dorsetshire.

Fig. 1. Appearance of trunks and roots of large Coni

ferous trees, and of trunks of Cycadites, in the black earth, which formed the soil of an ancient Forest in the Isle of Portland. (De la Beche.)

Fig. 2. Remarkable concentric Ridges of Stone, around the erect stump of a Fossil Tree in the Isle of Portland. See V. I. p. 372. Note. (Henslow.)

Fig. 3. Inclined position of the petrified stumps of large Coniferæ, and of the bed of black mould and pebbles in which they grew, near Lulworth Cove, on the Coast of Dorset. (Buckland.)

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PLATE 58. V. I. p. 370.

Cycas revoluta, producing Buds from the axillæ of the scales, or persistent bases of leaves, that form the false bark. Drawn from a plant in the conservatory of Lord Grenville at Dropmore, 1832.

PLATE 59. V. I. p. 371.

Fig. 1. Zamia pungens, with its fruit, as it grew at Walton on Thames, 1832, in the Conservatory of Lady Tankerville. (Lambert.)

Fig. 2. Transverse section of the trunk of Zamia horrida, from the Cape of Good Hope. (Buckland.)

Fig. 3. Transverse section of a young trunk of Cycas revoluta. See Geol. Trans. Lond. 1828. N. S. Vol. ii. Pt. 3. Pl. 46. (Buckland.)

PLATE 60. V. I. p. 373.

Fig. 1. Silicified trunk of Cycadites megalophillus, from
the Dirt bed in the Isle of Portland. (Original.)
Fig. 2. Portion of the base of Fig. 1. See V. I. p. 373,
Note. (Original.)

In Plates 60, 61, A represents the central mass of cellular tissue. B the single circle of radiating woody plates. C the circle of cellular tissue, surrounding B. And D the case or false Bark, surrounding C. And in Pl. 61, Fig. 1, b, represents a second circle of radiating woody plates.

PLATE 61. V. I. p. 373. Note.

Fig. 1. Silicified trunk of Cycadites microphyllus, from the Isle of Portland, with numerous buds rising from the axillæ of the Petioles. (Original.)

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