In the Oxford and Kimmeridge Clays water-worn trunks and branches of large pine-trees are often met with. An interesting deposit of these remains was brought to light by my youngest son (Mr. Reginald Mantell), when constructing the branch line of railway from the Great Western to Trowbridge, in Wilts. In the progress of the work, extensive sections were cut through the Oxford Clay, and laid bare a large quantity of drifted wood, much of which was not petrified, but in the state of bog-wood, and was used for fuel by the workmen. Trunks ten or twelve feet long were met with, to which serpulæ, oysters (_Ostrea delta_), and other shells were adherent. These vegetable remains were associated with Belemnites, Belemnoteuthides, Ammonites, &c.; and had evidently been drifted far out to sea by currents.[146] [146] See _Wond._ p. 502. Geol. Journal, vol. vi. p. 311. [Sidenote: FOSSIL CONIFEROUS WOOD.] Coniferous Wood in the Chalk formation.--The arenaceous limestones of the Greensand of Kent and Sussex abound, in some localities, in water-worn masses of coniferous wood, which are often perforated by boring mollusks, as _Teredo_, _Fistulana_, _Gastrochæna_, &c. In the Iguanodon quarry of Kentish rag, near Maidstone, large quantities of these remains occur, and Mr. Bensted has collected several cones belonging to different kinds of conifers; one of these appears to be a species of _Abies_, or Fir:[147] it was associated with fragments of trunks and branches, whose internal structure proved their relation to the fruit. _Plate V. fig. 2_, are microscopic views of transverse and longitudinal sections of this wood; 2_a_ shows the cellular tissue in a transverse slice, seen by reflected light; 2_b_ a vertical section in the direction of the medullary rays, exhibiting the vessels studded with single rows of glands. This wood occurs both in a calcareous and siliceous state; in some examples the external zones are calcareous, and the inner siliceous; in others the entire branch is changed into black flint, in which the coniferous structure is beautifully preserved. [147] It is figured and described as _Abies Benstedi_, by the Author. Geol. Proc. January, 1843. Near Willingdon, in Sussex (_Geol. S. E._ p. 172), a bed of sand, immediately beneath the Galt, contains a layer of water-worn fragments of stems and branches, of small size; they are generally perforated by _Gastrochænce_, and the cavities formed by these depredators are filled with particles of green chlorite sand. The structure of this wood is represented in _Plate V. fig. 3^a_ a transverse, and 3_b_ a vertical section, viewed by reflected light; in 3_b_ the vessels are dotted with two parallel longitudinal rows of very minute glands, arranged alternately, as in the Araucariæ; a fragment of one of the medullary rays is seen near the middle of the specimen.