Fossil Fruit of Pandanus. (_Popocarya._ _Bd._ pl. lxii. p. 503.)--The _Pandanaceæ_ are monocotyledonous trees, named Screw Pines from the spiral insertion of their long, rigid, sword-like leaves, along the stem; they are natives of hot climates, and abound in the groups of islands in the Pacific; being generally the first important vegetable tenants of the newly-formed Atols or coral-islands. As in the palms, the stem is supported near the base by long side-roots, which enable these trees to maintain an erect position, and flourish on the newly-elevated coral-reefs, where but little soil has accumulated. The existence of this tribe of plants during the secondary ages is known only by a single example of a fossil fruit, which was discovered by Mr. Page, of Bishport, in the Inferior Oolite, to the east of Charmouth, Dorsetshire, and is preserved in the museum at Oxford; no vestiges of the stems or foliage have been observed. [Illustration: Lign. 65. Fossil Wood with Teredines; _nat._ _London Clay, Regent's Park._ Fig. 1.--A polished transverse section, showing the tubes lined with spar. 2.--Portions of mineralized Teredines, seen in relief on the wood. ] This carpolithe, (for a detailed account and figures see _Bd._ p. 504, pl. lxiii.) is of the size of a large orange; the surface is covered with a stellated epicarpium, composed of hexagonal tubercles forming the summits of cells which occupy the entire circumference of the fruit. Each cell contains a single seed, usually hexagonal, resembling a small grain of rice, and is supported by a foot-stalk, formed of dense fibres; a character exhibited only by the seed-vessels of Pandanus. The fossil fruit differs from that of the recent Screw-pines in the seeds being neither inclosed in a hard nut, nor collected into drupes, but dispersed uniformly over the entire mass; this forms the essential generic distinction between them. Dr. Buckland has named this unique carpolithe _Podocarya_. (_Bd._ p. 505.) Wood perforated by Teredinæ. _Lign. 65._--The drifted trunks and masses of wood found in the London Clay, at Sheppey, Bognor, Bracklesham, &c., some of which belong to Palms, others to Conifers, and Dicotyledons, are commonly more or less perforated by the boring mollusks called _Teredo_, or _Teredina_; and remains of their testaceous tubes are often well preserved. The tortuous channels excavated in the wood by these borers, are lined or filled up with calcareous spar, indurated clay, or other mineral matter, of various shades of grey, blue, yellow, &c.; and the polished slabs of this fossil wood are beautifully diversified by the sections of the sparry tubes, crossed at right angles by the ligneous structure; as in the specimen _fig. 1, Lign. 65_, from the Canal in the Regent's Park.[169] [169] Slabs of this kind are generally kept by the lapidaries at Bognor, Worthing, &c. and sold at 2_s._ or 2_s._ 6_d._ each.