Fossil Fruits of the Isle of Sheppey.--This little island, which is situated in the mouth of the Thames, is entirely composed of the London Clay, with bands of septaria. On the north, there is a range of cliffs, about two hundred feet high, which is being continually undermined by the waves, and large masses of the clay are thrown down, and innumerable fruits, seeds, branches and stems of trees, and other fossils, are exposed on the strand at low-water. The vegetables are strongly impregnated with iron pyrites, and as this mineral speedily decomposes when exposed to the atmosphere, the choicest examples often fall to pieces, even when preserved in the cabinet.[163] The nodular masses of indurated clay, termed septaria, contain the best preserved and most durable fossils. The fossil fruits, or carpolithes, occur in such profusion, that a large collection can easily be made; they comprise several hundred species, few of which have been scientifically investigated.[164] [163] Mr. Bowerbank, who possesses an unrivalled collection of these fruits, keeps them in stopper-bottles filled with water, placing the different species separately, and labelling the phials. I have successfully employed mastic varnish, first wiping the specimens dry, and removing any saline efflorescence by means of raw cotton, and then brushing in the varnish with a stiff hair-pencil. [164] See vol. ii. Excursion to the Isle of Sheppey. Mr. Parkinson has given admirable figures of several of the Sheppey fruits, particularly of the large palm-like nuts, called "_petrified figs_" (_Org. Rem._ vol. i. pl. vi. vii. _Pict. Atlas_, pl. vi. vii.) M. Ad. Brongniart has named several in his _Prodrome_; but without figures the descriptions are useless to the student. Mr. Bowerbank has published two numbers of a work entitled, "_History of the Fossil Fruits of the London Clay_," with seventeen plates; from which I have selected a few subjects for illustration. The fruits described are the following: 1. Fruits having a downy structure, like the Cotton plant. 2. _Cucumites._ Seeds of plants of the cucumber family. _Lign._ 63, _fig._ 1 and 3. These fossil fruits so closely resemble the seeds of various members of the recent genus _Cucumis_, or Cucumber, comprising the Gourd, Water-melon, &c., both in outward form and internal structure, that there is no reasonable doubt of their belonging to plants of the same family; hence the name _Cucumites_ or fossil cucumbers. 3. Cones of a tree allied to the genus _Petrophila_, of New Holland. _Lign._ 63, _figs._ 2 and 8. 4. Seeds of the Bean family, some of which resemble those of the common Scarlet-runner. _Lign._ 63. _figs._ 5, 6, 7.